What's the source install guide for haproxy 2.2.2 and upgrade guide from 1.* or 2.1 *?

where to get the official source install guide for haproxy 2.2.2 ?
it’s better also to guide how to upgrade source install ( 1.* or 2.0.* or 2.1.8) .
since the haproxy version is 1.5.* in centos 7., it will be grateful to guide how to upgrade from 1.5. ( yum install ).

Don’t upgrade. Remove/Uninstall haproxy 1.5 cleanly and then you can build from sources.

You can find more informations about this in the file INSTALL in the tarball.