Allow Github history and rs-changelog element to specify a path

[jnurthen]

Is your feature request related to a problem? Please describe.
We have moved all the ARIA specs into a single repository. We would like to be able to continue to use rs-changelog and the respec commit history feature but currently we get all the specs in the repository

Describe the solution you'd like
Allow to specify the GH path parameter so we can limit commit history and changelog to a single file or return the path so we can filter it ourselves

Additional context
The GH path parameter does what we need but https://respec.org/github/ only returns hash and message

Describe any alternatives you've considered
Adding text to the commit messages to filter doesn't seem practical

Can you or your organization fund the work or help with development?
I can try to help.
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[jnurthen]

@sidvishnoi I think to fix this I need to make changes to https://github.com/speced/respec-web-services/blob/main/routes/github/lib/commits.ts to return the file path for each commit. Would it be possible to help me set up an environment so I can look into this as i don't seem to be able to build those services