doc/release-notes: towards uniform style (#306235)

* Minor tweaks to note text

* Elide "The" before attribute names at start of notes

* Turn version numbers into code blocks

* Turn branding into attribute names

* Add TODOs

* Turn code-block version numbers into plain text

... following discussion on Matrix.

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Co-authored-by: Weijia Wang <9713184+wegank@users.noreply.github.com>