Complement appdata.xml.in

Based on what is already available in the LinuxPhoneApps listing: https://linuxphoneapps.org/apps/eu.fl9.hamlocator.desktop I added some missing metainfo:
- Adds name
- Adds URLs for homepage, bugtracker and vcs-browser
- Adds categories
- Adds developer
- Adds description
- Adds screenshot
- Adds recommended and required controls

data/eu.fl9.hamlocator.appdata.xml.in

@@ -3,7 +3,29 @@
 	<id>eu.fl9.hamlocator.desktop</id>
 	<metadata_license>CC0-1.0</metadata_license>
 	<project_license>GPL-3.0-or-later</project_license>
+	<name>hamlocator</name>
+	<developer>
+		<name>Michał Rudowicz</name>
+	</developer>
+	<recommends>
+		<control>touch</control>
+	</recommends>
+	<requires>
+		<display_length compare="ge">360</display_length>
+	</requires>
 	<description>
-	  <p>No description</p>
+	  <p>Display a maidenhead locator</p>
 	</description>
+	<screenshots>
+		<screenshot type="default">
+			<image>https://git.sr.ht/~michalr/hamlocator/blob/main/media/screenshot.png</image>
+		</screenshot>
+	</screenshots>
+	<categories>
+		<category>GTK</category>
+		<category>GNOME</category>
+	</categories>
+	<url type="homepage">https://sr.ht/~michalr/hamlocator/</url>
+	<url type="bugtracker">https://todo.sr.ht/~michalr/hamlocator</url>
+	<url type="vcs-browser">https://git.sr.ht/~michalr/hamlocator</url>
 </component>