x11/kitty: kitty.conf(5) manual page improvement
Add an OVERVIEW section to that manpage, so that the NAME section has
only few words. See for example the output when visiting
https://man.freebsd.org/cgi/man.cgi?query=kitty.conf&apropos=1
Current rendering:
https://user-images.githubusercontent.com/192271/260857832-927f7a50-a95a-4fb0-9092-d39d0e52f1b1.png
PR: 273248
Reported by: Graham Perrin <grahamperrin@gmail.com>