Add the new node "User-defined Things" to the menu.
* Retrieving Nodes:: Retrieving nodes from a syntax tree.
* Accessing Node Information:: Accessing node information.
* Pattern Matching:: Pattern matching with query patterns.
+* User-defined Things:: User-defined ``Things'' and Navigation.
* Multiple Languages:: Parse text written in multiple languages.
* Tree-sitter Major Modes:: Develop major modes using tree-sitter.
* Tree-sitter C API:: Compare the C API and the ELisp API.