MAINTAINERS: ask maintainers to help keep their entries in this file upto date.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

MAINTAINERS

@@ -4,6 +4,8 @@ FFmpeg maintainers
 Below is a list of the people maintaining different parts of the
 FFmpeg code.
 
+Please try to keep entries where you are the maintainer upto date!
+
 
 Project Leader
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