Add indexed to TextChanged (ensdomains#14)

Author: makoto

abis/PublicResolver.json

@@ -512,7 +512,7 @@
         "type": "bytes32"
       },
       {
-        "indexed": false,
+        "indexed": true,
         "internalType": "string",
         "name": "indexedKey",
         "type": "string"

subgraph.yaml

@@ -100,7 +100,7 @@ dataSources:
           handler: handleNameChanged
         - event: 'PubkeyChanged(indexed bytes32,bytes32,bytes32)'
           handler: handlePubkeyChanged
-        - event: 'TextChanged(indexed bytes32,string,string)'
+        - event: 'TextChanged(indexed bytes32,indexed string,string)'
           handler: handleTextChanged
   - kind: ethereum/contract
     name: AuctionRegistrar