Man pages for dig/mdig/delv used `.. option:: +[no]bla` to describe two
options at once, and very old Sphinx does not support that [] in option
names.
Solution is to split negative and positive options into `+bla, +nobla`
form. In the end it improves readability because it transforms hard to
read strings with double brackets from
`+[no]subnet=addr[/prefix-length]` to
`+subnet=addr[/prefix-length], +nosubnet`.
As a side-effect it also allows easier linking to dig/mdig/delv options
using their name directly instead of always overriding the link target
to `+[no]bla` form.
Transformation was done using regex:
s/:: +\[no\]\(.*\)/:: +\1, +no\1
... and manual review around occurences matching regex
+no.*=
Fixes: #3301
0342dddce7