Add edit-distance-0.2.2.1 to stack.yaml

Convenience for `stack build`.

stack.yaml

@@ -11,6 +11,7 @@ extra-deps:
 - clock-0.7.2
 - cryptohash-sha256-0.11.100.1
 - ed25519-0.0.5.0
+- edit-distance-0.2.2.1
 - exceptions-0.8.2.1
 - hackage-security-0.5.2.2
 - hashable-1.2.4.0