RFR: Clarify use of (rel)-pool values

[Roger Calnan]

(rel)-pool values should not be used for affects versions, but can, along with tbd, be used in the fix version

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Commit messages:
 - Clarify that (rel)-pool values should not be used for affects versions, but can be used for fix versions

Changes: https://git.openjdk.org/guide/pull/134/files
  Webrev: https://webrevs.openjdk.org/?repo=guide&pr=134&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/guide/pull/134.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/134/head:pull/134

PR: https://git.openjdk.org/guide/pull/134