Add page about Lua module directory

Fixes #3034

docs/lua-modules/README.md

@@ -0,0 +1,9 @@
+# NodeMCU Lua modules directory
+
+Reviewing, hosting and thus potentially maintaining an ever growing list of NodeMCU Lua modules (the ones here) does not scale well for the project team. Instead, we give the community a chance - and the responsibility - to maintain a directory of Lua modules found in the wild through the [GitHub wiki](https://github.com/nodemcu/nodemcu-firmware/wiki/Lua-modules-directory).
+
+In the (hopefully not too distant) future, we will request that Lua modules to be hosted _in this repository_ come with a test program in whatever framework [we end up adopting](https://github.com/nodemcu/nodemcu-firmware/issues/2145).
+
+**A module being listed on the wiki does NOT mean the NodeMCU project team endorses it in any way.**
+
+→ [https://github.com/nodemcu/nodemcu-firmware/wiki/Lua-modules-directory](https://github.com/nodemcu/nodemcu-firmware/wiki/Lua-modules-directory)

mkdocs.yml

@@ -42,6 +42,7 @@ pages:
     - Lua Compact Debug (LCD): 'lcd.md'
     - Lua Flash Store (LFS): 'lfs.md'
 - Lua Modules:
+    - 'Lua modules directory': 'lua-modules/README.md'
     - 'bh1750': 'lua-modules/bh1750.md'
     - 'cohelper': 'lua-modules/cohelper.md'
     - 'ds18b20': 'lua-modules/ds18b20.md'