Fix two cross-references in BasisTranslator docstring (backport #12398)

[mergify]

Summary

Fix two cross-references in BasisTranslator docstring

Details and comments

I built this locally and it looks good.

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This is an automatic backport of pull request #12398 done by Mergify.

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[coveralls]

Pull Request Test Coverage Report for Build 9086392940

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.03%) to 89.653%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.02%
crates/qasm2/src/lex.rs	4	93.13%

Totals
Change from base Build 9085316335:	0.03%
Covered Lines:	62274
Relevant Lines:	69461

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💛 - Coveralls