Recently I added HTTP/2 protocol (derived from the formerly known SPDY protocol developed by Google) to my config since I haven’t found any references in my /etc/apache2 config files. It was quite simple to enable it.
a2enmod http2
A config file is needed too:
cat 01_http2.conf
Protocols h2 h2c http/1.1
Enable it:
a2enconf 01_http2
Restart server. Done.