doc/fate.texi: Mention that samples should be uploaded before pushing dependent commits

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

doc/fate.texi

@@ -155,6 +155,8 @@ space on each client, network bandwidth and so on benefit from smaller test case
 Also keep in mind older checkouts use existing sample files, that means in
 practice generally do not replace, remove or overwrite files as it likely would
 break older checkouts or releases.
+Also all needed samples for a commit should be uploaded, ideally 24
+hours, before the push.
 
 @example
 #First update your local samples copy: