RFR: 8357275: Locale.Builder.setLanguageTag should mention conversions made on language tag [v4]

[Justin Lu]

> It is not clear that `Locale.Builder.setLanguageTag(String)` accepts _extlang_ subtags in the input as well as what behavior occurs. Additionally, both this method and `Locale.forLanguageTag(String)` should mention their behavior when more than three _extlang_ subtags are provided. This PR clarifies the lack of context in the specification.

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

  CSR review - clarify that 3 extlang subtags is not a JDK specific condition

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Changes:
  - all: https://git.openjdk.org/jdk/pull/25309/files
  - new: https://git.openjdk.org/jdk/pull/25309/files/62714a26..1ee830e3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25309&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25309&range=02-03

  Stats: 6 lines in 1 file changed: 3 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/25309.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25309/head:pull/25309

PR: https://git.openjdk.org/jdk/pull/25309