Adjust link to AppStream metadata

Package_Management/Graphical_Tools/index.rst

@@ -81,7 +81,7 @@ On the **All** page, you can find a search button at the left edge of the header
 
    The search bar is shown when the search button is pressed when the **All** page is shown.
 
-Enter the search terms for the application you are looking for. The page will update to show appropriate matches as you enter text, finding applications based on their `AppStream`_ data (see the :ref:`Treasure example <examples_Treasure_data_dir>` for more information about this).
+Enter the search terms for the application you are looking for. The page will update to show appropriate matches as you enter text, finding applications based on their `AppStream metadata`_ (see the :ref:`Treasure example <examples_Treasure_data_dir>` for more information about this).
 
 .. figure:: images/gnome-software-search-results.png
    :align: center

links.txt

 .. _`Actions section`: https://python-gtk-3-tutorial.readthedocs.io/en/latest/application.html#actions
 .. _`AppStream`: https://www.freedesktop.org/software/appstream/docs/
+.. _`AppStream metadata`: https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html
 .. _`Building your first Flatpak`: http://docs.flatpak.org/en/latest/first-build.html
 .. _`community/librem-5`: https://matrix.to/#/#community-librem-5:talk.puri.sm
 .. _`community/librem-5-apps`: https://matrix.to/#/#community-librem-apps:talk.puri.sm