Install location of Documentation

[rbtylee]

While packaging gtkdialog for Bodhi Linux I noticed the install location for the examples and reference documentation is datadir/doc. Since installing from a deb file is very similar to compiling by

meson --prefix=/usr -Ddocs=true build
ninja -C build
sudo ninja -C build install 

This ends up with

gtkdialog/examples/* installed to /usr/share/doc/examples/*
gtkdialog/doc/reference/* installed to /usr/share/doc/reference/*

Examples and References should be installed to /usr/share/doc/gtkdialog

A trivial change to the meson build files fixes this:

+++ b/meson.build
@@ -26,7 +26,7 @@ endif
 if get_option('docs')
        subdir('doc')
        install_subdir(
-       'examples', install_dir : join_paths(get_option('datadir'), 'doc')
+       'examples', install_dir : join_paths(get_option('datadir'), 'doc', 'gtkdialog')
        )
 endif

and

+++ b/doc/meson.build
@@ -1,3 +1,3 @@
 install_subdir(
-       'reference', install_dir : join_paths(get_option('datadir'), 'doc')
+       'reference', install_dir : join_paths(get_option('datadir'), 'doc', 'gtkdialog')
        )