man-pages(7) says:
Filenames [...] are always in italics, except in the SYNOPSIS
section, [...]
Set filenames in italics, respectively change from boldface to italics.
While at it, mark whitespaces in commands as non-breakable via '\ '
to avoid unwanted hyphenation in the middle of commands.
* find/find.1 (-regex): Do the above.
(-exec,-execdir,-fprint): Likewise.