RFR: CODETOOLS-7903256: Fix typos and grammar issues in docs and comments

[Jonathan Gibbons]

Please review an update to fix typos and grammar errors found by inspection and by an IDE.

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

Commit messages:
 - CODETOOLS-7903256: Fix typos and grammar issues in docs and comments

Changes: https://git.openjdk.org/jtreg/pull/104/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=104&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903256
  Stats: 73 lines in 5 files changed: 0 ins; 1 del; 72 mod
  Patch: https://git.openjdk.org/jtreg/pull/104.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/104/head:pull/104

PR: https://git.openjdk.org/jtreg/pull/104