RFR: 8374752: Add more JLS links to javax.lang.model.element.*

[Joe Darcy]

The various modeling interfaces in javax.lang.model.element.* would benefit from more direct links to the corresponding JLS sections.

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Commit messages:
 - JDK-8374752: Add more JLS links to javax.lang.model.element.*

Changes: https://git.openjdk.org/jdk/pull/29103/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29103&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374752
  Stats: 42 lines in 7 files changed: 35 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/29103.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29103/head:pull/29103

PR: https://git.openjdk.org/jdk/pull/29103