doc: fix api docs style
Summary
doc/api/cluster.md
L337: Use the definition link
doc/api/deprecations.md
L106: Fix the definition link name
doc/api/errors.md
L901: Remove unused definition
Checklist
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make -j4 test
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tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
doc