RFR: JDK-8322979: Add informative discussion to Modifier [v4]

[Joe Darcy]

> Add a few apiNote concerning source-level modifiers that are not represented in java.lang.reflect.Modifier.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Reflow paragraph.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17338/files
  - new: https://git.openjdk.org/jdk/pull/17338/files/cc67f321..dabd8edd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17338&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17338&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17338.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17338/head:pull/17338

PR: https://git.openjdk.org/jdk/pull/17338