The tput command uses terminfo (from man tput):
tput [-Ttype] capname [parms ... ]
(…)
For a complete list of capabilities and the capname associated with each, see terminfo(5).
(…)
capname
indicates the capability from the terminfo database. When termcap support is compiled in, the termcap name for the capability is also accepted.
The civis and cnorm are documented in terminfo's man page:
cursor_invisible civis vi make cursor invisi‐
ble
cursor_normal cnorm ve make cursor appear
normal (undo
civis/cvvis)
In general, when you don't know which man page describes a particular command, you can search for it. In this case, I found the above by running man -K civis.