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Currently, nightly documentation is pushed automatically for each commit and on daily basis.

For release, automating it is tricky because we need to ensure that the version number is properly updated.
(removing alpha suffix at branch cut time and updating minor version at minor release)

For this reason, in release/2.1 we used manual-trigger to build and deploy doc for release.
This commit back port it to main.

For each release, once the version number is updated, running build_doc job from GHA will deploy the documentation automatically.