Add notice about AGP bug for 3rd-party modules.

love/src/jni/lua-modules/lua-modules-readme.txt

@@ -5,6 +5,7 @@ Each folder must contains:
   The LOCAL_MODULE_FILENAME must be set accordingly as ndk-build appends "lib" prefix from LOCAL_MODULE by default.
   For Lua includes and libraries, simply link the native library with "liblove".
   Caveat: If the library is meant to be loaded as require("my.library") then you MUST set LOCAL_MODULE_FILENAME to my.library (with dots)
+  Caveat 2: Due to bug in AGP, the LOCAL_MODULE_FILENAME must match with the folder name!
 * If your module interacts with Java-side, a file java.txt must contain where it should look Java source files.
   Example, if you have src/java/your/package/name/MyFile.java, then you need to write "src/java" in java.txt.
   If this file is absent, then your Java-side code will not be compiled along.