docs: man: fix bold in command TPs

[kmk3]

Reset the bold right after each command/argument.

Command used to check for issues:

git grep -E ' \\fR' -- src/man/*.in

Related commits:

• e91b9ff0f ("Deprecate --nodbus option", 2020-04-07) / PR #3265
• 5a612029b ("rename noautopulse to keep-config-pulse", 2021-05-13) / PR #4278
• d79547ca9 ("docs: warn about limitations of landlock", 2024-03-31) / PR #6302

This is a follow-up to #6451.

Relates to #6078.