RFR: JDK-8292576: Improve wording of AccessFlag-related specs

[Joe Darcy]

Spec refinement, including acting on some feedback received for JDK-8266670:

https://github.com/openjdk/jdk/pull/7445#discussion_r906846794

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

Commit messages:
 - JDK-8292576: Improve wording of AccessFlag-related specs

Changes: https://git.openjdk.org/jdk/pull/9912/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9912&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292576
  Stats: 12 lines in 2 files changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/9912.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9912/head:pull/9912

PR: https://git.openjdk.org/jdk/pull/9912