Installation update for CentOS 7

[OnRelay Support]

To install, upgrade or build sipXcom on CentOS 7 after its EOL date you must now change the yum repos to use vault.centos.org instead of mirror.centos.org, e.g. as follows:

sed -i 's|mirror.centos.org|vault.centos.org|g' /etc/yum.repos.d/CentOS-* 

sed -i 's|mirrorlist|#mirrorlist|g' /etc/yum.repos.d/CentOS-* 

sed -i 's|#baseurl|baseurl|g' /etc/yum.repos.d/CentOS-*

We have updated the 24.01 docs and build config accordingly.