Fix external link to github rendered page anchor

docs/source/extensions_tutorial/2_create_extension_spec_walkthrough.rst

@@ -8,7 +8,7 @@ and editing of the extension separately from the code that uses it. When startin
 recommend using the :nwb_extension_git:`ndx-template` repository, which automatically generates a repository with
 the appropriate directory structure.
 
-After you finish the instructions :nwb_extension_git:`here <ndx-template/blob/main/README.md#getting-started>`,
+After you finish the instructions :nwb_extension_git:`here <ndx-template/blob/main/README.md#user-content-getting-started>`,
 you should have a directory structure that looks like this
 
 .. code-block:: bash