RFR: 8311968: Clarify Three-letter time zone IDs in java.util.TimeZone [v2]

[Justin Lu]

> Please review this PR and associated [CSR](https://bugs.openjdk.org/browse/JDK-8311979) which links the full list of deprecated three-letter IDs in java.util.TimeZone
> 
> Although it is made apparent in TimeZone that certain 3-letter IDs are deprecated, it does not actually list them in the specification. In addition to linking the full list, it is clarified that not _all_ 3-letter IDs are deprecated, as there are quite a few that come from the tzdb.
> 
> This change links to the full list found in ZoneId.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Review: update wording to include mappings

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14861/files
  - new: https://git.openjdk.org/jdk/pull/14861/files/b9dfd4e5..3919ad19

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14861&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14861&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/14861.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14861/head:pull/14861

PR: https://git.openjdk.org/jdk/pull/14861