* docs: Simplify make rules for pandoc
This removes a --standalone duplicate and counter-productive
indirections like $(MANSECTION) because it prevents having more
than one and docs/Makefile hardcodes the section anyway.
* docs: Move quickemu_conf manual to section 5
Where it technically belongs... With the new make rules for pandoc, it's
actually much easier to manage manuals in several sections without much
overhead.
* docs: Remove potential quickemu_conf.1 leftover
Dridi Boukelmoune