Document pull-req #6424 in release-notes

Mention now allowed sequence of pushdatas in OP_RETURN outputs in
release notes.

doc/release-notes.md

@@ -105,6 +105,16 @@ In this version, it is only enforced for peers that send protocol versions
 removed. It is recommended to update SPV clients to check for the `NODE_BLOOM`
 service bit for nodes that report versions newer than 70011.
 
+Any sequence of pushdatas in OP_RETURN outputs now allowed
+----------------------------------------------------------
+
+Previously OP_RETURN outputs with a payload were only relayed and mined if they
+had a single pushdata. This restriction has been lifted to allow any
+combination of data pushes and numeric constant opcodes (OP_1 to OP_16). The
+limit on OP_RETURN output size is now applied to the entire serialized
+scriptPubKey, 83 bytes by default. (the previous 80 byte default plus three
+bytes overhead)
+
 Merkle branches removed from wallet
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