fix typo and add engine-api note

content/docs/developers/geth-developer/Private-Network.md

@@ -457,7 +457,7 @@ This account can then be unlocked and some ether sent to Node 2, using the follo
 
 ```javascript
 // unlock account
-personal.unlock(eth.accounts[0])
+personal.unlockAccount(eth.accounts[0])
 
 // send some Wei
 eth.sendTransaction({to: "0xc94d95a5106270775351eecfe43f97e8e75e59e8", from: eth.accounts[0], value: 25000})

content/docs/interacting_with_geth/RPC/server.md

@@ -116,6 +116,12 @@ The following table summarizes the relative strengths and weaknesses of each tra
 As a general rule IPC is most secure because it is limited to interactions on the local machine and cannot be exposed to external traffic. It can also be used
 to subscribe to events. HTTP is a familiar and idempotent transport that closes connections between requests and can therefore have lower overall overheads if the number of requests is fairly low. Websockets provides a continuous open channel that can enable event subscriptions and streaming and handle large volumes of requests with smaller per-message overheads.
 
+## Engine-API
+
+The Engine-API is a set of RPC methods that enable communication between Geth and the [consensus client](/docs/getting_started/consensus-clients.md). These are not designed to be exposed to the user - instead they are called automatically by the clients when they need to exchange information. The Engine API is enabled by default - the user is not required to pass any instruction to Geth to enable these methods.
+
+Read more in the [Engine API spec](https://github.com/ethereum/execution-apis/blob/main/src/engine/specification.md).
+
 
 ## Summary