docs: set new server release version (#1779)

Author: dudantas

src/core.hpp

@@ -14,7 +14,7 @@ static constexpr auto AUTHENTICATOR_PERIOD = 30U;
 
 // SERVER_MAJOR_VERSION is the actual full version of the server, including minor and patch numbers.
 // This is intended for internal use to identify the exact state of the server (release) software.
-static constexpr auto SERVER_RELEASE_VERSION = "3.0.0";
+static constexpr auto SERVER_RELEASE_VERSION = "3.1.0";
 static constexpr auto CLIENT_VERSION = 1321;
 
 #define CLIENT_VERSION_UPPER (CLIENT_VERSION / 100)