CHANGELOG: add PR numbers

CHANGELOG.md

@@ -1,13 +1,13 @@
 # 2.2.0
 __added__
-- Added `Block.calculateTarget` for difficulty calculations
-- Added `Block.prototype.checkProofOfWork`
-- Added `opcodes.OP_CHECKLOCKTIMEVERIFY` alias for `OP_NOP2`,
-- Added `script.number.[encode/decode]` for CScriptNum-encoded `Buffer`s
-- Added `TransactionBuilder.prototype.setLockTime`
+- Added `Block.calculateTarget` for difficulty calculations (#509)
+- Added `Block.prototype.checkProofOfWork` (#509)
+- Added `opcodes.OP_CHECKLOCKTIMEVERIFY` alias for `OP_NOP2` (#511)
+- Added `script.number.[encode/decode]` for CScriptNum-encoded `Buffer`s (#516)
+- Added `TransactionBuilder.prototype.setLockTime` (#507)
 
 __fixed__
-- Bumped `typeforce` version to fix erroneous error message from `types.Hash*bit` types
+- Bumped `typeforce` version to fix erroneous error message from `types.Hash*bit` types (#534)
 
 
 # 2.1.4