add documentation index for doc/ as README.md

README.md

@@ -32,6 +32,7 @@ Further documentation
 - Forum: https://forum.luanti.org/
 - GitHub: https://github.com/luanti-org/luanti/
 - [Developer documentation](doc/developing/)
+- [Documentation index](doc/README.md)
 - [doc/](doc/) directory of source distribution
 
 Default controls

doc/README.md

@@ -0,0 +1,29 @@
+# Documentation Index
+
+The following is a list of documentation files and a brief description to aid
+in locating documentation (sorted alphabetically).
+
+## Lua
+
+- [Builtin Entities](builtin_entities.md): Documentation of core engine entities.
+- [Client-side API](client_lua_api.md): Documentation on client side lua API
+    enviorment.
+- [Formspec Toolkit API](fst_api.txt): Documentation on formspec toolkit.
+- [Menu API](menu_lua_api.md): Documentation lua API for menu enviorment.
+- [Mod API](lua_api.md): Documentation on lua API for mod enviorment.
+
+## Formats and Content
+
+- [Texture Packs](texture_packs.md): Documentation on Luanti's texture packs system.
+- [World Format](world_format.md): Documentation on Luanti world format.
+
+## Protocals
+
+- [Protocol](protocol.txt): Documentation on Luanti's network protocol.
+
+## Misc.
+
+- [Android information](android.md): Documentation relating to Luanti on the Android platform.
+- [Docker Server](docker_server.md): Documentation on Luanti's Docker server.
+- [Luanti Development Direction](direction.md): Official Luanti development direction information.
+- [Major Breakages List](breakages.md): Documentation of breaking changes.