Add Xandikos as another DAV server.

app/src/main/res/values/arrays.xml

@@ -224,6 +224,7 @@
     <item>@string/caldav_server_owncloud</item>
     <item>@string/caldav_server_sabredav</item>
     <item>@string/caldav_server_synology_calendar</item>
+    <item>@string/caldav_server_xandikos</item>
     <item>@string/caldav_server_other</item>
     <item>@string/caldav_server_unknown</item>
   </string-array>
@@ -239,4 +240,4 @@
     <item>-1</item>
   </integer-array>
 
-</resources>
+</resources>

app/src/main/res/values/keys.xml

@@ -24,6 +24,7 @@
   <string name="caldav_server_openxchange">Open-Xchange</string>
   <string name="caldav_server_synology_calendar">Synology Calendar</string>
   <string name="caldav_server_mailbox_org">Mailbox.org</string>
+  <string name="caldav_server_xandikos">Xandikos</string>
 
   <string name="url_davx5">https://tasks.org/davx5</string>
   <string name="url_caldav">https://tasks.org/caldav</string>