doc: proofread changelogs/unreleased

changelogs/unreleased/fix-string-dequoting.md

changelogs/unreleased/gh-4763-introduce-map-to-sql.md

changelogs/unreleased/gh-6251-operator-brackets.md

changelogs/unreleased/gh-6751-olson-timezones.md

changelogs/unreleased/gh-6793-datetime-set-with-tzoffset.md

changelogs/unreleased/gh-7076-tz-attributes.md

changelogs/unreleased/gh-7089-applier-vclock-race.md

changelogs/unreleased/gh-7113-rev-tree-iters-gap-tracking.md

...eased/gh-7129-improve-check-for-dangerous-select-calls.md

changelogs/unreleased/gh-7132-sql-insertion-crash.md