D400 rule ("ends-in-period") adds dot at the end of RST headings which break sphinx builds

[AKuederle]

When using sphinx-gallery you regularly write example files that need to start with a RST-style heading in the module docstring.

"""
My example
==========

My example explanation
"""
print("my_example")

The autofix rule for D400 adds a dot at the end of the underline, making it invalid RST and breaking the Sphinx build

After transformation:

"""
My example
==========.

My example explanation
"""
print("my_example")

Tested in latest ruff version (0.1.6)

[charliermarsh]

Closed by #8929 -- thanks for reporting!