avoid pinging hard-coded server for netinstall.yaml

groupsUrl is optional and should be commented out by default
also this URL is 404
also only chakra would ever want to ping the chakra server anyways

src/modules/netinstall/netinstall.conf

@@ -1,7 +1,10 @@
 ---
 # This is the URL that is retrieved to get the netinstall groups-and-packages
-# data (which should be in the format described in netinstall.yaml).
-groupsUrl: http://chakraos.org/netinstall.php
+# data (which should be in the format described in netinstall.yaml), e.g.:
+#   groupsUrl: http://example.org/netinstall.php
+# or it can be a locally installed file:
+#   groupsUrl: file:///usr/share/calamares/netinstall.yaml
+# groupsUrl: file:///usr/share/calamares/netinstall.yaml
 
 # If the installation can proceed without netinstall (e.g. the Live CD
 # can create a working installed system, but netinstall is preferred