[docs] add note about the AST not being public API (#7113)

site/content/docs/04-compile-time.md

@@ -178,7 +178,7 @@ ast: object = svelte.parse(
 
 ---
 
-The `parse` function parses a component, returning only its abstract syntax tree. Unlike compiling with the `generate: false` option, this will not perform any validation or other analysis of the component beyond parsing it.
+The `parse` function parses a component, returning only its abstract syntax tree. Unlike compiling with the `generate: false` option, this will not perform any validation or other analysis of the component beyond parsing it. Note that the returned AST is not considered public API, so breaking changes could occur at any point in time.
 
 
 ```js