chore: update readme

Author: jun06t

enum-compatibility/README.md

@@ -1,22 +1,49 @@
-# Unary(Simple) gRPC sample
+# Enum compatibility check
+## Premise
+Old proto is following.
 
-## Compile
+```proto
+message HelloReply {
+  string message = 1;
+  enum Role {
+    NONE     = 0;
+    STANDARD = 1;
+    PREMIUM  = 2;
+    ULTIMATE = 3;
+  }
+  Role role = 2;
+}
 ```
-make proto
+
+Then I update like this.
+```proto
+message HelloReply {
+  string message = 1;
+  RoleType role = 2;
+}
+
+enum RoleType {
+  NONE     = 0;
+  STANDARD = 1;
+  PREMIUM  = 2;
+  ULTIMATE = 3;
+}
 ```
 
-## Run gRPC server
-Server depends on new enum proto.
+## Confirm behaviour
+### Run gRPC server
+Server depends on new enum proto ``RoleType``.
 ```
 go run server/main.go
 ```
 
-## Run gRRC Client
-Client depends on old enum proto.
+### Run gRRC Client
+Client depends on old enum proto ``HelloReply.Role``.
 ```
 go run client/main.go
 ```
 
+### Result
 Then it returns
 ```
 2024/11/13 08:50:49 Reply:  Hello alice