Document how to install dependencies

[strowk]

I'm currently cannot build this, because of error

gtk/gtkx.h: No such file or directory

I tried to figure out which package to install to have this and I see several choices from
apt-cache search libgtk | grep libgtk3 :

libgtk3-perl - Perl bindings for the GTK+ graphical user interface library
libgtk3-nocsd0 - Library to disable Gtk+ 3 client side decorations (CSD)
libgtk3-simplelist-perl - Perl simple interface to GTK+ 3's complex MVC list widget
libgtk3-webkit2-perl - WebKit2 bindings for Perl
libgtk3.0-cil - CLI binding for the GTK+ 3.0 toolkit
libgtk3.0-cil-dev - CLI binding for the GTK+ toolkit 3.0

I'm not sure which to install. Should it be libgtk3.0-cil-dev ?
I think it would be better to have a ready apt-get command in documentation, explaining exactly what package should be installed.

[strowk]

I found out - it was sudo apt install libgtk-3-dev :)

Still believe it should be in documentation though.

[puttehi]

Had the same thoughts so opened a PR to help future users