Fix typo

Author: mcarans

installers/flatpak/space.oolite.Oolite.metainfo.xml

@@ -57,7 +57,7 @@
     </screenshot>
     <screenshot>
       <image>https://raw.githubusercontent.com/OoliteProject/oolite/1.92-maintenance/installers/flatpak/oolite-001.png</image>
-      <caption>Access the expansion pack manager and quick reference guides om the start screen.</caption>
+      <caption>Access the expansion pack manager and quick reference guides on the start screen.</caption>
     </screenshot>
     <screenshot>
       <image>https://raw.githubusercontent.com/OoliteProject/oolite/1.92-maintenance/installers/flatpak/oolite-002.png</image>