trivial: Improve desktop-app description a little

References to packaging aren't ideal in a world where bundles exist, and
general application listings are derived from metainfo data, so clarify
what desktop-entry files are for.

Author: ximion

docs/xml/metainfo-desktopapp.xml

@@ -11,7 +11,8 @@
 		<title>Introduction</title>
 		<para>
 			A desktop application is interactive software that presents a graphical interface to the user.
-			To appear in application listings, the packaged application must include a <ulink url="https://specifications.freedesktop.org/desktop-entry-spec/latest/">Freedesktop <filename>.desktop</filename></ulink> file.
+			To appear in menus, the desktop application must include a
+			<ulink url="https://specifications.freedesktop.org/desktop-entry-spec/latest/">Freedesktop <filename>.desktop</filename></ulink> file.
 		</para>
 		<para>
 			AppStream generators may pull data from the preexisting <filename>.desktop</filename> files to represent an application in the AppStream metadata pool. Upstream projects should