bip-0300: Ensure tx fee commitment itself has zero value so sidechain coins can't get burned

Author: luke-jr

bip-0300.mediawiki

@@ -410,7 +410,7 @@ M6 is invalid if:
 
 * The blinded hash of M6 does NOT match one of the approved Bundle-hashes.  (In other words: M6 must first be approved by 13,150 upvotes.)
 * The first output of M6 is NOT an OP_DRIVECHAIN. (This OP_DRIVECHAIN becomes the new CTIP. In other words: all non-withdrawn coins are paid back to the sidechain.)
-* The second output is NOT an OP_RETURN script of exactly 10 bytes, of which 8 bytes are a serialized Bitcoin amount.
+* The second output is NOT a zero-value OP_RETURN script of exactly 10 bytes, of which 8 bytes are a serialized Bitcoin amount.
 * The txn fee of M6 is NOT exactly equal to the amount of the previous bullet point.
 * There are additional OP_DRIVECHAIN outputs after the first one.