RFR: Various clarifications

[Jesper Wilhelmsson]

Minor updates to clarify and fix typos and other minor "bugs".

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Commit messages:
 - Various clarifications

Changes: https://git.openjdk.org/guide/pull/109/files
 Webrev: https://webrevs.openjdk.org/?repo=guide&pr=109&range=00
  Stats: 28 lines in 4 files changed: 13 ins; 0 del; 15 mod
  Patch: https://git.openjdk.org/guide/pull/109.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/109/head:pull/109

PR: https://git.openjdk.org/guide/pull/109