doc: fix double spaces in ERR_TLS_INVALID_PROTOCOL_METHOD

Signed-off-by: Daijiro Wachi <daijiro.wachi@gmail.com>

Author: watilde

doc/api/errors.md

@@ -3104,7 +3104,7 @@ The context must be a `SecureContext`.
 
 ### `ERR_TLS_INVALID_PROTOCOL_METHOD`
 
-The specified  `secureProtocol` method is invalid. It is  either unknown, or
+The specified `secureProtocol` method is invalid. It is either unknown, or
 disabled because it is insecure.
 
 <a id="ERR_TLS_INVALID_PROTOCOL_VERSION"></a>