Fix some @see NSEdoc

https://secwiki.org/w/Nmap/Code_Standards#NSEdoc_best-practices
Update sip.lua NSEdoc

https://secwiki.org/w/Nmap/Code_Standards#NSEdoc_best-practices
Clean up smbauth.lua NSEdoc

https://secwiki.org/w/Nmap/Code_Standards#NSEdoc_best-practices
Clean up xmpp.lua NSEdoc

https://secwiki.org/w/Nmap/Code_Standards#NSEdoc_best-practices