docs: review red/white stripes

[ThomasWaldmann]

In the docs there are some sections / features marked with red and white stripes, indicating potentially unstable (IIRC) stuff.

Some of that stuff is there since rather long, so, if there are no known issues, we can remove the stripes for borg 1.4.

[ThomasWaldmann]

search * for "experimental":

pattern / patterns-from

Check whether we need to fix / improve matching behaviour and if so, fix it (keep experimental status). See also #7964.

If not, remove "experimental" and keep matching as is.

borg-recreate (see borg.css)

Guess we can remove the "experimental" there.

Quite some people have used that and no complaints.

[ThomasWaldmann]

borg-recreate: see #8197.