Changelog: Add 3.2

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

Changelog

 Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
-version <next>:
+version 3.2:
 - libopenmpt demuxer
 - tee protocol
 - Changed metadata print option to accept general urls