[Base] GetAndroidThreadJniEnv capitals, move JNI usage tips there

src/xenia/base/main_android.h

@@ -38,9 +38,18 @@ void ShutdownAndroidAppFromMainThread();
 // configuration.
 int32_t GetAndroidApiLevel();
 
+// Useful notes about JNI usage on Android within Xenia:
+// - All static libraries defining JNI native functions must be linked to shared
+//   libraries via LOCAL_WHOLE_STATIC_LIBRARIES.
+// - If method or field IDs are cached, a global reference to the class needs to
+//   be held - it prevents the class from being unloaded by the class loaders
+//   (in a way that would make the IDs invalid when it's reloaded).
+// - GetStringUTFChars (UTF-8) returns null-terminated strings, GetStringChars
+//   (UTF-16) does not.
+
 // May return null if not in a Java VM process, or in case of a failure to
 // attach on a non-main thread.
-JNIEnv* GetAndroidThreadJNIEnv();
+JNIEnv* GetAndroidThreadJniEnv();
 // Returns the global reference if in an application context, or null otherwise.
 // This is the application context, not the activity one, because multiple
 // activities may be running in one process.