fix copy-paste error

gnunicorn · gnunicorn · commit 8962a88319ce · 2020-04-24T15:31:59.000+02:00
diff --git a/README.md b/README.md
@@ -230,7 +230,7 @@ Ensure you replace `ALICE_BOOTNODE_ID_HERE` with the node ID from the output of
 
 ## License
 
-Substrate is [GPL 3.0 licensed](LICENSE).
+Polkadot is [GPL 3.0 licensed](LICENSE).
 
 ## Important Notice
 
