RFR: 8342469: Improve API documentation for java.lang.classfile.instruction [v3]

[Chen Liang]

> Improve the documentation for classfile instructions. Includes links to all opcodes, usage notes for instructions, and other various fixes.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Further facelift
 - Merge branch 'master' of https://github.com/openjdk/jdk into docs/cf-instruction
 - Merge branch 'master' of https://github.com/openjdk/jdk into docs/cf-instruction
 - Typos, long lines
 - Labels
 - Wip instr

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Changes: https://git.openjdk.org/jdk/pull/21625/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21625&range=02
  Stats: 2380 lines in 38 files changed: 1976 ins; 27 del; 377 mod
  Patch: https://git.openjdk.org/jdk/pull/21625.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21625/head:pull/21625

PR: https://git.openjdk.org/jdk/pull/21625