Add a Doxyfile and preliminary module-level docs.

src/database.js.h

@@ -1,5 +1,13 @@
 #pragma once
 
+/**
+** \defgroup database_js Database Interface
+** Exposes a key-value store interface to script.
+** @{
+*/
+
 typedef struct JSContext JSContext;
 
 void tf_database_register(JSContext* context);
+
+/** @} */