Fix syntax in coap doc

docs/en/modules/coap.md

@@ -2,15 +2,17 @@
 The CoAP module provides a simple implementation according to [CoAP](http://tools.ietf.org/html/rfc7252) protocol.
 The basic endpoint server part is based on [microcoap](https://github.com/1248/microcoap), and many other code reference [libcoap](https://github.com/obgm/libcoap).
 
-This Module implement both Client and Server side. GET/PUT/POST/DELETE is partially supported by Client. Server can regist Lua function and varibles. No Observe or Discover supported right now.
+This module implements both the client and the server side. GET/PUT/POST/DELETE is partially supported by the client. Server can register Lua functions and varibles. No observe or discover supported yet.
 
 ## Caution
-CoAP Module is only in the very early stage and not complete right now.
+This module is only in the very early stage and not complete yet.
 
 ## Constants
-`coap.CON`, `coap.NON` is the request type.
+Constants for various functions.
 
-`coap.TEXT_PLAIN`, `coap.LINKFORMAT`, `coap.XML`, `coap.OCTET_STREAM`, `coap.EXI`, `coap.JSON` is the content type.
+`coap.CON`, `coap.NON` represent the request types.
+
+`coap.TEXT_PLAIN`, `coap.LINKFORMAT`, `coap.XML`, `coap.OCTET_STREAM`, `coap.EXI`, `coap.JSON` represent content types.
 
 ## coap.Client()
 
@@ -71,17 +73,16 @@ cs:func("myfun") -- post coap://192.168.18.103:5683/v1/f/myfun will call myfun
 
 # CoAP Client
 
-
 ## coap.client:get()
 
-Issue a GET request to the server.
+Issues a GET request to the server.
 
 #### Syntax
-`coap.client:get( type, uri, payload )`
+`coap.client:get(type, uri, [payload])`
 
 #### Parameters
-- `type` coap.CON, coap.NON, default to CON. when type is CON, and request failed, the request will retry another 4 times before giving up.
+- `type` `coap.CON`, `coap.NON`, defaults to CON. If the type is CON and request fails, the library retries four more times before giving up.
-- `uri` the uri such as coap://192.168.18.103:5683/v1/v/myvar, only IP is supported.
+- `uri` the URI such as "coap://192.168.18.103:5683/v1/v/myvar", only IP addresses are supported i.e. no hostname resoltion.
 - `payload` optional, the payload will be put in the payload section of the request.
 
 #### Returns
@@ -89,14 +90,14 @@ Issue a GET request to the server.
 
 ## coap.client:put()
 
-Issue a PUT request to the server.
+Issues a PUT request to the server.
 
 #### Syntax
-`coap.client:put( type, uri, payload )`
+`coap.client:put(type, uri, [payload])`
 
 #### Parameters
-- `type` coap.CON, coap.NON, default to CON. when type is CON, and request failed, the request will retry another 4 times before giving up.
+- `type` `coap.CON`, `coap.NON`, defaults to CON. If the type is CON and request fails, the library retries four more times before giving up.
-- `uri` the uri such as coap://192.168.18.103:5683/v1/v/myvar, only IP is supported.
+- `uri` the URI such as "coap://192.168.18.103:5683/v1/v/myvar", only IP addresses are supported i.e. no hostname resoltion.
 - `payload` optional, the payload will be put in the payload section of the request.
 
 #### Returns
@@ -104,13 +105,13 @@ Issue a PUT request to the server.
 
 ## coap.client:post()
 
-Issue a POST request to the server.
+Issues a POST request to the server.
 
 #### Syntax
-`coap.client:post( type, uri, payload )`
+`coap.client:post(type, uri, [payload])`
 
 #### Parameters
-- `type` coap.CON, coap.NON, default to CON. when type is CON, and request failed, the request will retry another 4 times before giving up.
+- `type` coap.CON, coap.NON, defaults to CON. when type is CON, and request failed, the request will retry another 4 times before giving up.
 - `uri` the uri such as coap://192.168.18.103:5683/v1/v/myvar, only IP is supported.
 - `payload` optional, the payload will be put in the payload section of the request.
 
@@ -119,40 +120,38 @@ Issue a POST request to the server.
 
 ## coap.client:delete()
 
-Issue a DELETE request to the server.
+Issues a DELETE request to the server.
 
 #### Syntax
-`coap.client:delete( type, uri, payload )`
+`coap.client:delete(type, uri, [payload])`
 
 #### Parameters
-- `type` coap.CON, coap.NON, default to CON. when type is CON, and request failed, the request will retry another 4 times before giving up.
+- `type` `coap.CON`, `coap.NON`, defaults to CON. If the type is CON and request fails, the library retries four more times before giving up.
-- `uri` the uri such as coap://192.168.18.103:5683/v1/v/myvar, only IP is supported.
+- `uri` the URI such as "coap://192.168.18.103:5683/v1/v/myvar", only IP addresses are supported i.e. no hostname resoltion.
 - `payload` optional, the payload will be put in the payload section of the request.
 
 #### Returns
 `nil`
 
-
 # CoAP Server
 
-
 ## coap.server:listen()
 
-Start the CoAP server on the given port.
+Starts the CoAP server on the given port.
 
 #### Syntax
-`coap.server:listen( port, ip )`
+`coap.server:listen(port, [ip])`
 
 #### Parameters
-- `port` server port (number).
+- `port` server port (number)
-- `ip` optional.
+- `ip` optional IP address
 
 #### Returns
 `nil`
 
 ## coap.server:close()
 
-Close the CoAP server.
+Closes the CoAP server.
 
 #### Syntax
 `coap.server:close()`
@@ -165,14 +164,14 @@ none
 
 ## coap.server:var()
 
-Regist a Lua variable as an endpoint in the server. the varible value then can be GET by a client via GET method, represented as an [URI](http://tools.ietf.org/html/rfc7252#section-6) to client. The endpoint path for varialble is '/v1/v/'.
+Registers a Lua variable as an endpoint in the server. the variable value then can be retrieved by a client via GET method, represented as an [URI](http://tools.ietf.org/html/rfc7252#section-6) to the client. The endpoint path for varialble is '/v1/v/'.
 
 #### Syntax
-`coap.server:var( name, content_type )`
+`coap.server:var(name, [content_type])`
 
 #### Parameters
-- `name` the Lua variable's name.
+- `name` the Lua variable's name
-- `content_type` optional, default to coap.TEXT_PLAIN, see [Content Negotiation](http://tools.ietf.org/html/rfc7252#section-5.5.4)
+- `content_type` optional, defaults to `coap.TEXT_PLAIN`, see [Content Negotiation](http://tools.ietf.org/html/rfc7252#section-5.5.4)
 
 #### Returns
 `nil`
@@ -192,19 +191,18 @@ cs:var("all", coap.JSON) -- sets content type to json
 
 ## coap.server:func()
 
-Regist a Lua function as an endpoint in the server. the function then can be called by a client via POST method. represented as an [URI](http://tools.ietf.org/html/rfc7252#section-6) to client. The endpoint path for function is '/v1/f/'. 
+Registers a Lua function as an endpoint in the server. The function then can be called by a client via POST method. represented as an [URI](http://tools.ietf.org/html/rfc7252#section-6) to the client. The endpoint path for function is '/v1/f/'. 
 
-When the client issues a POST request to this URI, the payload will be passed to the function as parameter. the function's return value will be the payload in the message to the client.
+When the client issues a POST request to this URI, the payload will be passed to the function as parameter. The function's return value will be the payload in the message to the client.
 
-The function registed SHOULD be accept ONLY ONE string type parameter, and return ONE string value or return nothing.
+The function registered SHOULD accept ONLY ONE string type parameter, and return ONE string value or return nothing.
-When the client issue 
 
 #### Syntax
-`coap.server:func( name, content_type )`
+`coap.server:func(name, [content_type])`
 
 #### Parameters
-- `name` the Lua function's name.
+- `name` the Lua function's name
-- `content_type` optional, default to coap.TEXT_PLAIN, see [Content Negotiation](http://tools.ietf.org/html/rfc7252#section-5.5.4)
+- `content_type` optional, defaults to `coap.TEXT_PLAIN`, see [Content Negotiation](http://tools.ietf.org/html/rfc7252#section-5.5.4)
 
 #### Returns
 `nil`