[FAB-12257] allow balance-transfer for doscovery

Balance-Transfer docker-compose file does not have the parameters
-CORE_PEER_GOSSIP_BOOTSTRAP and -CORE_PEER_GOSSIP_EXTERNALENDPOINT
assigned to its peers. This impacts the usage of Fabric v1.2 discovery
feature by apps like Blockchain Explorer

Change-Id: I2ca8adc57af34a0442e91a956b97e754088bba74
Signed-off-by: Cláudio Ramos <claudiovtramos@gmail.com>

balance-transfer/artifacts/docker-compose.yaml

@@ -74,6 +74,8 @@ services:
       - CORE_PEER_ID=peer0.org1.example.com
       - CORE_PEER_LOCALMSPID=Org1MSP
       - CORE_PEER_ADDRESS=peer0.org1.example.com:7051
+      - CORE_PEER_GOSSIP_BOOTSTRAP=peer1.org1.example.com:7051      
+      - CORE_PEER_GOSSIP_EXTERNALENDPOINT=peer0.org1.example.com:7051
     ports:
       - 7051:7051
       - 7053:7053
@@ -91,6 +93,8 @@ services:
       - CORE_PEER_ID=peer1.org1.example.com
       - CORE_PEER_LOCALMSPID=Org1MSP
       - CORE_PEER_ADDRESS=peer1.org1.example.com:7051
+      - CORE_PEER_GOSSIP_BOOTSTRAP=peer0.org1.example.com:7051      
+      - CORE_PEER_GOSSIP_EXTERNALENDPOINT=peer1.org1.example.com:7051
     ports:
       - 7056:7051
       - 7058:7053
@@ -108,6 +112,8 @@ services:
       - CORE_PEER_ID=peer0.org2.example.com
       - CORE_PEER_LOCALMSPID=Org2MSP
       - CORE_PEER_ADDRESS=peer0.org2.example.com:7051
+      - CORE_PEER_GOSSIP_BOOTSTRAP=peer1.org2.example.com:7051      
+      - CORE_PEER_GOSSIP_EXTERNALENDPOINT=peer0.org2.example.com:7051
     ports:
       - 8051:7051
       - 8053:7053
@@ -125,6 +131,8 @@ services:
       - CORE_PEER_ID=peer1.org2.example.com
       - CORE_PEER_LOCALMSPID=Org2MSP
       - CORE_PEER_ADDRESS=peer1.org2.example.com:7051
+      - CORE_PEER_GOSSIP_BOOTSTRAP=peer0.org2.example.com:7051      
+      - CORE_PEER_GOSSIP_EXTERNALENDPOINT=peer1.org2.example.com:7051
     ports:
       - 8056:7051
       - 8058:7053