Add CI/CD from docs-templates repo

[cmuellner]

This adds the CI/CD scripts from the docs-templates repo.

[cmuellner]

@apazos, @kito-cheng, or @wmat, please review.

[apazos]

That is what I was planning to do, to use the workflow from the docs template.
I actually pushed a draft PR and tested it in my branch: https://github.com/apazos/riscv-c-api-doc/actions/runs/12242758695
It worked fine.
But I included both *.pdf and *.html files in the artifacts. You might want to add them both.
This means in the "Upload Build Artifacts" action, add both files:

 path: |
    ${{ github.workspace }}/build/*.pdf
    ${{ github.workspace }}/build/*.html

[cmuellner]

@apazos, my PRs were not meant to overtake the plans of others.

Given we had different levels of CI/CD support in the three repos (TC, CAPI, ASM), I just wanted to establish a common baseline. The background is, that we got PRs for some repos that add a dependabot action, and I want to avoid the repos diverging even more.

Feel free to provide PRs that enhance the CI/CD pipelines as you've planned.

[cmuellner]

@wmat, ping. Please approve this PR. It would be great to merge this as well.

[wmat]

LGTM thanks.

[apazos]

Hi @cmuellner, no worries. Looking at https://github.com/riscv-non-isa/riscv-asm-manual/releases, it seems it already included all the files from the build directory, both html and pdf files. I thought we would have to fix some rule to make sure they appear under Assets.