[CentOS] httpd/sites-available directory

I just received some advice from a colleague of a colleague over at 
openssl.org.  But they use debian.  Please look at this and help me out 
on how Centos7 handles this:

Note the comment of the location of virtualhost config files. Centos7 
does not have a "man a2ensite".

thanks

Rewriterules and https.  Actually, looking at what you have doesn't
really tell me why it gets applied to everything and not just the
webmail.  However, I'd say that your roundcubemail.conf is much
overworked.  We use something like that on openssl.org, but it
generally looks like this:

     <VirtualHost *:80>
             ServerAdmin webmaster at localhost
             ServerName ${HOSTNAME}
             ServerAlias ${HOSTALIASES}
     
             Redirect permanent /https://${HOSTNAME}/
     </VirtualHost>

Since you already know that the host is correct and that's the port 80
virtualhost, there's no point testing that with those RewriteCond you
have.  Also, Redirect is faster and preferable to RewriteRule for this
kind of stuff, seehttps://httpd.apache.org/docs/2.4/rewrite/avoid.html

Also, specifically for virtualhost config files, they should be
located in sites-available/ rather than conf.d/, see 'man a2ensite'.
conf.d/ is older style configuration of general stuff...  or well,
that's at least true for Debian, I'm not sure this is specific for
Debian distributions and their derivates or if it's a native Apache
thing.  You'll have to check the manuals to confirm.