How to find and install missed man page or section in linux

Two options:
1) web
2) in server repositories

1) In web - just google it
https://www.google.com/search?q=man+7+signal
Will result in smth like http://man7.org/linux/man-pages/man7/signal.7.html

2) In server
$ man kill
# no signals details , most likely in "SEE ALSO .... signals(7)"

$ man 7 signal
No manual entry for signal in section 7

$ yum provides */signal.7.gz
...
#man-pages-3.53-5.el7.noarch : Man (manual) pages from the Linux Documentation Project
#Repo : rhel-7-server-rpms-master
#Matched from:
#Filename : /usr/share/man/man7/signal.7.gz
..

$ sudo yum install man-pages

$ man 7 signal