docs(api): Fix typo

Author: tony

docs/api.md

@@ -10,7 +10,8 @@ tmux via python API calls.
 ## Internals
 
 :::{warning}
-These APIs are purely internal not covered by versioning policies, they can and will break between versions.
+Internal APIs are **not** covered by version policies. They can break or be removed between minor versions.
+
 If you need an internal API stabilized please [file an issue](https://github.com/tmux-python/tmuxp/issues).
 :::