Install appdata

data/Makefile.am

@@ -10,6 +10,9 @@ desktop_in_files = gnome-sudoku.desktop.in.in
 desktop_DATA = $(desktop_in_files:.desktop.in.in=.desktop)
 @INTLTOOL_DESKTOP_RULE@
 
+appdatadir = $(datadir)/appdata
+appdata_DATA = gnome-sudoku.appdata.xml
+
 pixmapdir = $(datadir)/gnome-sudoku/images/
 pixmap_DATA = footprints.png
 
@@ -31,6 +34,7 @@ man_MANS = gnome-sudoku.6
 EXTRA_DIST = \
 	$(pixmap_DATA)	\
 	$(desktop_DATA)	\
+	$(appdata_DATA)	\
 	$(puzzle_DATA)	\
 	$(ui_DATA)	\
 	$(gsettings_in_file) \

data/gnome-sudoku.appdata.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<application>
+<id type="desktop">gnome-sudoku.desktop</id>
+<licence>CC0</licence>
+<description>
+<p>
+GNOME Sudoku has a simple unobstrusive interface
+while still providing features that make playing difficult Sudoku more fun.
+All games are automatically saved when you quit so you don't have to worry about saving games.
+You can always come back to any game you've played.
+</p>
+<p>
+If you like to play on paper, you can print games out.
+You can choose how many games you want to print per page and what difficulty of
+games you want to print: as a result, GNOME Sudoku can act a renewable Sudoku Book for you.
+</p>
+<p>
+Each game is assigned a "difficulty" score - its algorithm generally does a good
+job matching the difficulty rankings typically given by newspapers and websites.
+You can also see detailed difficulty information about how the computer solved
+the puzzle.
+</p>
+</description>
+<url type="homepage">https://wiki.gnome.org/GnomeSudoku</url>
+</application>