docs: add note about loading native library

Author: itsaky

README.md

@@ -18,6 +18,12 @@ implementation 'com.itsaky.androidide.treesitter:android-tree-sitter:<version>'
 implementation 'com.itsaky.androidide.treesitter:tree-sitter-<language>:<version>'
 ```
 
+Before using tree sitter, load the native library when appropriate (e.g. in the `onCreate()` method of your `Application` class, or in your activity) :
+
+```java
+TreeSitter.loadLibrary();
+```
+
 The following grammars have been published to Maven central :
 
 - Java