<i18n dev> RFR: 8367704: Fix minor documentation issues in java.time.**

[Pavel Rappo]

Please review this documentation-only change, which I believe does **NOT** require CSR.

The change touches java.time.** classes that I happen to have been using a lot recently. While the diff is pretty self-describing, here's the summary of what I did:

* used a comma separator for some big integer values, to improve readability;
* fixed a few typos and grammar.

While I'm open to discuss the change, I also have some questions. Note: I'm not attempting to address those questions in this PR.

* What's the significance of the second argument in Duration.between(Temporal, Temporal) being exclusive? For example, would the result of the following call be different if the second argument was inclusive?

        Duration.between(Instant.ofEpochSecond(1), Instant.ofEpochSecond(2))

  Are there any cases here where that distinction matters?

* In many cases, the following phrase is used throughout documentation:

    > positive or negative

    While the intent is clearly to stress the directed nature of values, shouldn't we -- for completeness -- also mention zero where applicable?

* What's the significance of title-case for Java Time-Scale? FWIW, the documentation also uses "Java time-scale".
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### Progress
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- [x] Change must not contain extraneous whitespace
- [x] Commit message must refer to an issue



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Commit messages:
 - Use comma as a decimal separator
 - Fix Duration.abs
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/27296/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27296&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367704
  Stats: 26 lines in 6 files changed: 0 ins; 0 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/27296.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27296/head:pull/27296

PR: https://git.openjdk.org/jdk/pull/27296