[CentOS-docs] Added BackupPC Guide

Karanbir Singh wrote:
> 
> Sometimes for arch specific notes, a comment box at the bottom of the 
> page should be enough - but then again that is something for the 
> EditGroup to decide I guess.
> 

In the one instance I've encountered this (dovecot config setting on 
x86_64 that was documented in the release notes), I added a note inline 
for the config setting for x86_64 like so:

protocols = imap imaps pop3 pop3s
mail_location = maildir:~/Maildir
pop3_uidl_format = %08Xu%08Xv
# Required on x86_64 kernels
login_process_size = 64

In hind sight, that's probably not the clearest way to do it and 
formatting it in a separate note box would probably make it stand out more.

Equally, where config stuff has changed between dists (eg, C4 > C5), 
I've stated the guide was written for C5 but added notes affecting C4 
where I've known of differences (for example, 
HowTos/postfix_restrictions where some of the config syntax changed 
between postfix versions).

WRT your point above, IMHO major information (potential show stoppers) 
such as dist or arch specific notes would probably be best included in a 
note at the *top* of the document rather than the bottom. I'd be a 
little miffed at reading a whole document only to discover right at the 
bottom of the page that there is an arch or dist gotcha that applies to 
me. IHMO if there are clear advantages to running on a particular dist 
or arch it should be clearly stated up front.