docs: ensure CollectAndCollapse is part of the public API

[mrossinek]

Summary

As discussed offline, this ensures that the CollectAndCollapse transpiler pass is actually part of the public API.

Details and comments

I am not sure whether this requires a release note... 🤔

[qiskit-bot]

One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[jakelishman]

Thanks Max. If you feel like a release note would be particularly useful to people, feel free to add one, but we probably don't really need one - this was announced as if it were public API, already was intended to be, and we don't typically have release notes for documentation-only changes.

Let me know either way and I'll tag for merge.

[coveralls]

Pull Request Test Coverage Report for Build 10668553853

Details

• 2 of 2 (100.0%) changed or added relevant lines in 2 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 89.163%

---

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	5	92.48%

Totals
Change from base Build 10667735969:	0.02%
Covered Lines:	71841
Relevant Lines:	80573

---

💛 - Coveralls

[mrossinek]

Thanks Max. If you feel like a release note would be particularly useful to people, feel free to add one, but we probably don't really need one - this was announced as if it were public API, already was intended to be, and we don't typically have release notes for documentation-only changes.

Let me know either way and I'll tag for merge.

Sounds good 👍 I don't think a release note would add much value here so I would go with this as is