docs: add tools/docs/gen-renames.py

docs: add tools/docs/gen-renames.py

Add a new script that wraps git to trawl the repository history for
renames of .rst files in the Documentation/ directory.

Example usage:

  tools/docs/gen-renames.py --rev v6.17-rc3 > Documentation/.renames.txt

The output format is simply:

  <old path> SPACE <new path> NEWLINE

where neither <old path> nor <new path> contain the Documentation/
prefix or the .rst suffix. The file is sorted alphabetically.

We can suggest rerunning the script for future renames (and squash the
resulting change) or rerun it periodically to keep the file up to date.

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20250905144608.577449-2-vegard.nossum@oracle.com>