Add HITL operators to standard provider index docs

[Lohith625]

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Was generative AI tooling used to co-author this PR?

• Yes

Generated-by: ChatGPT following the guidelines

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Summary

Improve the discoverability of Human-in-the-Loop (HITL) operators in the Standard provider documentation.

What is changed

• Added a dedicated HITL operators documentation page under the Standard provider operators docs
• Briefly explains what Human-in-the-Loop (HITL) operators are and their intended use cases
• Lists the available HITL operators provided by the Standard provider
• Added links to:
  • The existing Python API reference for detailed operator documentation
  • The HITL tutorial for end-to-end usage examples

Why this is needed

Currently, HITL operators are only visible through the generated Python API documentation, which makes them difficult to discover for users browsing the Standard provider operator docs.

This change aligns HITL operators with how other operators are documented and improves overall documentation clarity and usability.

closes #60614

[Lohith625]

Note on spelling wordlist update

During CI, the documentation spellcheck step failed due to the terms HITL / hitl being flagged as unknown words.
To address this, I added these terms to docs/spelling_wordlist.txt so the spellcheck passes cleanly and consistently across builds.

If this addition is unnecessary or if there is a preferred alternative (for example, different casing or quoting), I’m very happy to adjust and learn from the feedback.

[shahar1]

Note on spelling wordlist update

During CI, the documentation spellcheck step failed due to the terms HITL / hitl being flagged as unknown words. To address this, I added these terms to docs/spelling_wordlist.txt so the spellcheck passes cleanly and consistently across builds.

If this addition is unnecessary or if there is a preferred alternative (for example, different casing or quoting), I’m very happy to adjust and learn from the feedback.

I see no issue having them there, they are indeed commonly used.

[github-actions]

Backport successfully created: v3-1-test

Status	Branch	Result
✅	v3-1-test