Merge #193: Typo, sigwit -> segwit

5a9c518 Typo, sigwit -> segwit (Marco D'Agostini)

Pull request description:

Tree-SHA512: f6499953a55a76feb0d26a74d0862476cc65376750d6054be1b1c91979764170d64937754bce82cc1fc00fc47e03687ea6bd43925fe1ec3a62a40c7c2461a123

Author: petertodd

release-notes.md

@@ -22,7 +22,7 @@ Other changes:
 
 Now supports segwit, which breaks the API in minor ways from v0.8.0. This
 version introduces lots of new API functionality related to this, such as the
-new `CScriptWitness`, `CTxInWitness`, `CTxWitness`, new sigwit-specific logic
+new `CScriptWitness`, `CTxInWitness`, `CTxWitness`, new segwit-specific logic
 in `SignatureHash()` etc.