Fix link to HIPE
#### Background
-The Freeze Ledgers transaction implements the functionality proposed in [Indy HIPE 0162 Frozen Ledgers](https://github.com/esplinr/indy-hipe/blob/master/text/0162-frozen-ledgers/README.md). That HIPE contains useful information for understanding this feature.
+The Freeze Ledgers transaction implements the functionality proposed in [Indy HIPE 0162 Frozen Ledgers](https://github.com/hyperledger/indy-hipe/blob/master/text/0162-frozen-ledgers/README.md). That HIPE contains useful information for understanding this feature.
#### Key Information
