man.1: Improve search + spdx
People are often stunned by robust manual search functionality on
the community discord, so improve introductory doc regarding search by:
+ explain what search related flags do instead of using similies
+ consolidate and standardize search options in synopsis and usage
+ mention that a page or file can be specified in synopsis and example
+ call regular expressions expression, which searches to re_format(7)
+ crossreference the regular expression manual instead of egrep(1)
+ improve MANPATH xref flow and explanation, matching MAILPATH in sh(1)
+ mark up aditional semantics for their inclusion in apropos
While here:
+ use consistent spacing and form (Ql) for quoted literals
+ clean a few linter errors regarding self xref and nospace
+ reset a list width to indent for consistency with style.mdoc
+ tidy examples + align files + tag spdx
Outstanding:
- example 3 shows no results on a typical bsdinstall'd system
MFC after: 3 days
Reviewed by: elliejs, emaste, imp, Jessica Hawkwell, jlduran
Approved by: imp
(cherry picked from commit 46a9fb7287f41eedf321d81a68a826f231d11bfe)