RFR: JDK-8276772: Refine javax.lang.model docs [v3]

[Joe Darcy]

> Pass over javax.lang.model docs for some minor cleanups and improvements.
> 
> Before pushing, I'll do any needed copyright updates and reflow paragraphs.

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

  Final cleanups, update copyright, etc.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6286/files
  - new: https://git.openjdk.java.net/jdk/pull/6286/files/57b3982c..757353c3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6286&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6286&range=01-02

  Stats: 13 lines in 8 files changed: 2 ins; 0 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6286.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6286/head:pull/6286

PR: https://git.openjdk.java.net/jdk/pull/6286