fix misspelled words (#650)

diff --git a/server/govern/README.md b/server/govern/README.md
index 99143e0..ea0e8d4 100644
--- a/server/govern/README.md
+++ b/server/govern/README.md
@@ -46,7 +46,7 @@
 import roa "github.com/apache/servicecomb-service-center/pkg/rest"
 
 func init() {
-    roa.RegisterServent(&HelloService{})
+    roa.RegisterServant(&HelloService{})
 }
 ```