Update some documentation

assets/linux/com.mtkennerly.madamiru.metainfo.xml

@@ -10,7 +10,14 @@
     <url type="bugtracker">https://github.com/mtkennerly/madamiru/issues</url>
     <url type="translate">https://crowdin.com/project/madamiru</url>
     <description>
-        <p>Madamiru is a cross-platform video player that can automatically play and shuffle multiple videos at once in a grid layout.</p>
+        <p>Madamiru is a cross-platform media player written in Rust that can automatically play and shuffle multiple videos, images, and songs at once in a grid layout.</p>
+        <p>Features:</p>
+        <ul>
+            <li>Video formats: AVI, M4V, MKV, MOV, MP4, WebM</li>
+            <li>Image formats: BMP, GIF, ICO, JPEG, PNG, TIFF, SVG, WebP</li>
+            <li>Audio formats: FLAC, M4A, MP3, WAV</li>
+            <li>Subtitles are supported within MKV (but not as separate files)</li>
+        </ul>
     </description>
     <categories>
         <category>AudioVideo</category>
@@ -36,6 +43,12 @@
         <keyword>CLI</keyword>
         <keyword>GUI</keyword>
     </keywords>
+    <screenshots>
+        <screenshot type="default">
+            <image type="source">https://raw.githubusercontent.com/mtkennerly/madamiru/v0.1.0/docs/sample-gui.png</image>
+            <caption>Graphical user interface</caption>
+        </screenshot>
+    </screenshots>
     <content_rating type="oars-1.1" />
     <launchable type="desktop-id">com.mtkennerly.madamiru.desktop</launchable>
     <releases>