Fix typo in comment

lib/CalDAV/Plugin.php

@@ -720,7 +720,7 @@ public function beforeWriteContent($path, DAV\IFile $node, &$data, &$modified)
             return;
         }
 
-        // We're onyl interested in ICalendarObject nodes that are inside of a
+        // We're only interested in ICalendarObject nodes that are inside of a
         // real calendar. This is to avoid triggering validation and scheduling
         // for non-calendars (such as an inbox).
         list($parent) = Uri\split($path);