docs: document [json: ETitle] in vlib/json/README.md too

vlib/json/README.md

@@ -1,9 +1,14 @@
 ## Description:
 
-`json` provides encoding/decoding of V data structures to/from JSON.
-
+The `json` module provides encoding/decoding of V data structures to/from JSON.
+For more details, see also the 
+[JSON section of the V documentation](https://github.com/vlang/v/blob/master/doc/docs.md#json)
 ## Examples:
 
+Here is an example of encoding and decoding a V struct with several fields.
+Note that you can specify different names in the json encoding for the fields,
+and that you can skip fields too, if needed.
+
 ```v
 import json
 
@@ -14,23 +19,28 @@ enum JobTitle {
 }
 
 struct Employee {
+mut:
 	name   string
+	family string   [json: '-'] // this field will be skipped
 	age    int
 	salary f32
-	title  JobTitle
+	title  JobTitle [json: 'ETitle'] // the key for this field will be 'MyTitle', not 'title'
 }
 
 fn main() {
-	x := Employee{'Peter', 28, 95000.5, .worker}
+	x := Employee{'Peter', 'Begins', 28, 95000.5, .worker}
 	println(x)
-	//
 	s := json.encode(x)
-	println('Employee x: ${s}')
-	assert s == '{"name":"Peter","age":28,"salary":95000.5,"title":"worker"}'
-	//
-	y := json.decode(Employee, s)!
-	//
-	println(y)
+	println('JSON encoding of employee x: ${s}')
+	assert s == '{"name":"Peter","age":28,"salary":95000.5,"ETitle":"worker"}'
+	mut y := json.decode(Employee, s)!
+	assert y != x
+	assert y.family == ''
+	y.family = 'Begins'
 	assert y == x
+	println(y)
+	ss := json.encode(y)
+	println('JSON encoding of employee y: ${ss}')
+	assert ss == s
 }
 ```