12.4R/errata: beautify the open issues area

[grahamperrin]

Summary

An issue that is published as an erratum (at a page such as this) is inherently important, no need to describe it as such. Without the table effect, we're free from the two rendering issues that were pictured by @emaste at https://reviews.freebsd.org/D38999#887707.

Whilst here: add a missing full stop (.) and make one sentence per line.

Origin of this diff:

• https://github.com/freebsd/freebsd-doc/compare/main...grahamperrin:freebsd-doc:patch-2.diff.

Test Plan

Preview in GitHub:

• https://github.com/grahamperrin/freebsd-doc/blob/patch-2/website/content/en/releases/12.4R/errata.adoc#open-issues.

[emaste]

I liked the table effect but with only one note we really don't need it, and as you say it fixes the rendering issue so let's do it

[grahamperrin]

Thanks. If someone else would like to commit, go ahead.

(Right now, I can't work with Git at the command line.)

[grahamperrin]

Housekeeping: patch-2 deleted from https://github.com/grahamperrin/freebsd-doc/branches.