[doc] Replace Nm with more appropriate macros
[doc] Replace Nm with more appropriate macros

in manpage such as Fl, Ar, Ev, Em, etc.

[ci skip]

jwakely/ledger,jwakely/ledger,afh/ledger,ledger/ledger,duncanmortimer/ledger,paulbdavis/ledger,afh/ledger,paulbdavis/ledger,ledger/ledger,ledger/ledger,paulbdavis/ledger,paulbdavis/ledger,jwakely/ledger,ledger/ledger,duncanmortimer/ledger,duncanmortimer/ledger,jwakely/ledger,duncanmortimer/ledger,jwakely/ledger,paulbdavis/ledger,paulbdavis/ledger,afh/ledger,duncanmortimer/ledger,jwakely/ledger,paulbdavis/ledger,duncanmortimer/ledger,ledger/ledger,duncanmortimer/ledger,afh/ledger,jwakely/ledger,afh/ledger