Update default type map to None for TypeMap generation

[rly]

Changed the default type map to None for a clean TypeMap generation.

Summary of changes

• Fix Schema documentation does not reflect the latest version #601

Checklist

For all schema changes:

• Add release notes for the PR to docs/format/source/format_release_notes.rst.
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.
• Make sure that hdmf-common-schema points to the latest release and not the latest commit on the main branch.

If this is the first schema change after a schema release (i.e., the version string in core/nwb.namespace.yaml does not
end in "-alpha"), then:

• Update the version string in core/nwb.namespace.yaml and core/nwb.file.yaml to the next major/minor/patch
  version with the suffix "-alpha". For example, if the current version is 2.4.0 and this is a minor change, then the
  new version string should be "2.5.0-alpha".
• Update the value of the version variable in docs/format/source/conf.py to the next version without the
  suffix "-alpha", e.g., "2.5.0".
• Update the value of the release variable in docs/format/source/conf.py to the next version with the suffix
  "-alpha", e.g., "2.5.0-alpha".
• Add a new section in the release notes docs/format/source/format_release_notes.rst for the new version
  with the date "Upcoming" in parentheses.

[oruebel]

Docs build shows the below error. Other recent builds are passing, so I think this is related to the change here.

 Traceback (most recent call last):
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/sphinx/events.py", line 441, in emit
        results.append(listener.handler(self._app, *args))
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/checkouts/663/docs/format/source/conf.py", line 35, in run_doc_autogen
        generate_docs()
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/hdmf_docutils/generate_format_docs.py", line 461, in main
        namespace_catalog = load_namespace(namespace_file=core_namespace_file,
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/hdmf_docutils/generate_format_docs.py", line 121, in load_namespace
        namespace_catalog = NamespaceCatalog(default_namespace,
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/hdmf/utils.py", line 591, in func_call
        pargs = _check_args(args, kwargs)
                ^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/hdmf/utils.py", line 584, in _check_args
        raise ExceptionType(msg)
    TypeError: NamespaceCatalog.__init__: incorrect type for 'core_namespaces' (got 'str', expected 'list')
    
    The above exception was the direct cause of the following exception:
    
    Traceback (most recent call last):
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/sphinx/cmd/build.py", line 414, in build_main
        app = Sphinx(
              ^^^^^^^
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/sphinx/application.py", line 340, in __init__
        self._init_builder()
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/sphinx/application.py", line 430, in _init_builder
        self.events.emit('builder-inited')
      File "/home/docs/checkouts/readthedocs.org/user_builds/nwb-schema/envs/663/lib/python3.12/site-packages/sphinx/events.py", line 452, in emit
        raise ExtensionError(
    sphinx.errors.ExtensionError: Handler <function run_doc_autogen at 0x748303c03b00> for event 'builder-inited' threw an exception (exception: NamespaceCatalog.__init__: incorrect type for 'core_namespaces' (got 'str', expected 'list'))

[rly]

Sorry for the premature request for review. You're right. hdmf-dev/hdmf-docutils#95 and a release should fix it