Add the private type to the docs.

Julian · Julian · commit 2c74a61a58fc · 2023-02-19T12:06:09.000+02:00
This may need to be public anyhow I guess, we shall see.
diff --git a/docs/api.rst b/docs/api.rst
@@ -18,6 +18,11 @@ API Reference
    :undoc-members:
 
 
+.. autoclass:: referencing._core._MaybeInSubresource
+   :members:
+   :undoc-members:
+
+
 Submodules
 ----------
 
