RFR: 8333828: Use value javadoc tag in java.lang.{Float, Double}

[Joe Darcy]

Use the value tag to make the javadoc for various format-related constants more informative to readers. Currently the information is available by following the "Constant Field Values" link.

I'll reflow the paragraphs before a push.

-------------

Commit messages:
 - JDK-8333828: Use value javadoc tag in java.lang.{Float, Double}

Changes: https://git.openjdk.org/jdk/pull/19607/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19607&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333828
  Stats: 10 lines in 2 files changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/19607.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19607/head:pull/19607

PR: https://git.openjdk.org/jdk/pull/19607