fix typo

Author: gtcooke94

internal/envconfig/xds.go

@@ -64,7 +64,7 @@ var (
 	// https://github.com/grpc/proposal/blob/master/A82-xds-system-root-certs.md.
 	XDSSystemRootCertsEnabled = boolFromEnv("GRPC_EXPERIMENTAL_XDS_SYSTEM_ROOT_CERTS", false)
 
-	// XDSSpiffeEnabled controls is SPIFFE Bundle Maps can be used as roots of
+	// XDSSpiffeEnabled controls if SPIFFE Bundle Maps can be used as roots of
 	// trust.  For more details, see:
 	// https://github.com/grpc/proposal/blob/master/A87-mtls-spiffe-support.md
 	XDSSpiffeEnabled = boolFromEnv("GRPC_EXPERIMENTAL_XDS_MTLS_SPIFFE", false)