fix error in CHANGELOG.md (#39)

Author: davidjsonn

CHANGELOG.md

@@ -174,7 +174,7 @@
         - **Passport hash** in every other case.
     * Now a passport can't be registered with both the public key and the hash.
 * Added the second registration contract `Registration2` which works with the updated circuits. Updated circuits utilize five public inputs and always output a passport hash.
-    * The `Passport` struct has changed, hence chenging `register()`, `revoke()`, and `reissueIdentity()` methods signatures.
+    * The `Passport` struct has changed, hence changing `register()`, `revoke()`, and `reissueIdentity()` methods signatures.
 * Updated `PRSASHA1Authenticator` contract to accept an RSA exponent as an initialization parameter to support the wider range of passports.
 * New constants have been added:
     1. **Passport dispatchers**