RFR: Clarified the Affects version section [v3]

[Joakim Nordström]

> Clarification for the [Affects version section](https://openjdk.org/guide/#usage-of-the-rel-na-label)
> 
> * Removed some newlines so things are kept in one paragraph
> * Changed some wording to make the _don'ts_ a bit clearer

Joakim Nordström has updated the pull request incrementally with two additional commits since the last revision:

 - Added some newlines
 - Removed some text

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

Changes:
  - all: https://git.openjdk.org/guide/pull/170/files
  - new: https://git.openjdk.org/guide/pull/170/files/c009bc42..2536d310

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=guide&pr=170&range=02
 - incr: https://webrevs.openjdk.org/?repo=guide&pr=170&range=01-02

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/guide/pull/170.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/170/head:pull/170

PR: https://git.openjdk.org/guide/pull/170