Update README.md

Author: Qiu233

README.md

@@ -7,9 +7,30 @@ Add to `lakefile.lean`:
 require binary from git "https://github.com/Lean-zh/binary.git"
 ```
 
-In file:
+## Deriving
+```lean
+import Binary
+
+open Binary Primitive
 
+open LE in
+@[bin_enum 4 [0, 2]]
+inductive A where
+  | a -- 0
+  | b (s : Int32) -- 2
+deriving Encode, Decode
+
+open BE in
+structure B where
+  s : Int32
+deriving Encode, Decode
+
+#eval Put.run 128 (put (A.b 1234))
 ```
+
+## Serialization/Deserialization
+
+```lean
 import Binary
 
 open Binary Primitive.LE
@@ -20,7 +41,7 @@ Or open `Primitive.BE` when you want to handle data in big endian.
 
 The recommended usage is
 
-```
+```lean
 import Binary
 
 open Binary Primitive