NegotitationServer-->NegotiationServer typo fix

cd NegotitationServer did not work,
cd NegotiationServer  does :)

samples/Management/README.md

@@ -12,7 +12,7 @@ This sample shows the usage of Azure SignalR Service Management SDK.
 ### Start the negotiation server
 
 ```
-cd NegotitationServer
+cd NegotiationServer
 dotnet user-secrets set Azure:SignalR:ConnectionString "<Connection String>"
 dotnet run
 ```