Merge PR #2093: A URL to abci-spec.md fixed

docs/sdk/core/app1.md

@@ -469,7 +469,7 @@ Tendermint consensus engine. It would be initialized by a Genesis file, and it
 would be driven by blocks of transactions committed by the underlying Tendermint
 consensus. We'll talk more about ABCI and how this all works a bit later, but
 feel free to check the
-[specification](https://github.com/tendermint/tendermint/blob/master/docs/abci-spec.md).
+[specification](https://github.com/tendermint/tendermint/blob/master/docs/app-dev/abci-spec.md).
 We'll also see how to connect our app to a complete suite of components
 for running and using a live blockchain application.
 

docs/sdk/core/app4.md

@@ -16,7 +16,7 @@ here we will introduce the other ABCI requests sent by Tendermint, and
 how we can use them to build more advanced applications. For a more complete
 depiction of the ABCI and how its used, see
 [the
-specification](https://github.com/tendermint/tendermint/blob/master/docs/abci-spec.md)
+specification](https://github.com/tendermint/tendermint/blob/master/docs/app-dev/abci-spec.md)
 
 ## InitChain