docs: add keywords to autoapi docs

[Revathyvenugopal162]

Docs CI/CD is split into 3 workflows:

Nightly Docs Build & Deploy

• Runs every night on an 8-core Ubuntu machine.
• Builds full docs with autosummary and autoapi.
• Only the development docs are deployed nightly.

CI/CD on Pull Requests (PRs)

• Builds documentation without autoapi or autosummary.
• Does not deploy any docs.
• Will soon support PR previews using Ansys Actions.

Release CI/CD

• Triggers on releases.
• Runs full doc build, full testing, and release actions.
• Deploys stable documentation.

🧹 Cleanup

• Removed all actions related to:
• release branches from the normal workflow.
• Stable doc deployment from non-release workflows.