Add "JSON-RPC API Playground" section

Author: Destiner

public/content/developers/docs/apis/json-rpc/index.md

@@ -28,8 +28,6 @@ An internal API is also used for inter-client communication within a node - that
 
 [Read the full JSON-RPC API spec on GitHub](https://github.com/ethereum/execution-apis).
 
-You can also use the [interactive JSON-RPC API playground](https://ethereum-json-rpc.com).
-
 ## Conventions {#conventions}
 
 ### Hex value encoding {#hex-encoding}
@@ -135,6 +133,10 @@ A handful of core JSON-RPC methods require data from the Ethereum network, and f
 - [eth_getUncleByBlockHashAndIndex](#eth_getunclebyblockhashandindex)
 - [eth_getUncleByBlockNumberAndIndex](#eth_getunclebyblocknumberandindex)
 
+## JSON-RPC API Playground
+
+You can use the [playground tool](https://ethereum-json-rpc.com) to discover and try out the API methods. It also shows you which methods and networks are supported by various node providers.
+
 ## JSON-RPC API Methods {#json-rpc-methods}
 
 ### web3_clientVersion {#web3_clientversion}