docs(context): add example comments for ShouldBind* methods (#4428)

- Added detailed example for ShouldBindJSON
- Added consistent descriptive comments for ShouldBindXML, ShouldBindQuery, ShouldBindYAML, ShouldBindTOML, ShouldBindPlain, ShouldBindHeader, ShouldBindUri
- Makes binding method usage clearer for new users

Author: AtoriUzawa

context.go

@@ -830,41 +830,71 @@ func (c *Context) ShouldBind(obj any) error {
 }
 
 // ShouldBindJSON is a shortcut for c.ShouldBindWith(obj, binding.JSON).
+//
+// Example:
+//
+//	POST /user
+//	Content-Type: application/json
+//
+//	Request Body:
+//	{
+//		"name": "Manu",
+//		"age": 20
+//	}
+//
+//	type User struct {
+//		Name string `json:"name"`
+//		Age  int    `json:"age"`
+//	}
+//
+//	var user User
+//	if err := c.ShouldBindJSON(&user); err != nil {
+//		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+//		return
+//	}
+//	c.JSON(http.StatusOK, user)
 func (c *Context) ShouldBindJSON(obj any) error {
 	return c.ShouldBindWith(obj, binding.JSON)
 }
 
 // ShouldBindXML is a shortcut for c.ShouldBindWith(obj, binding.XML).
+// It works like ShouldBindJSON but binds the request body as XML data.
 func (c *Context) ShouldBindXML(obj any) error {
 	return c.ShouldBindWith(obj, binding.XML)
 }
 
 // ShouldBindQuery is a shortcut for c.ShouldBindWith(obj, binding.Query).
+// It works like ShouldBindJSON but binds query parameters from the URL.
 func (c *Context) ShouldBindQuery(obj any) error {
 	return c.ShouldBindWith(obj, binding.Query)
 }
 
 // ShouldBindYAML is a shortcut for c.ShouldBindWith(obj, binding.YAML).
+// It works like ShouldBindJSON but binds the request body as YAML data.
 func (c *Context) ShouldBindYAML(obj any) error {
 	return c.ShouldBindWith(obj, binding.YAML)
 }
 
 // ShouldBindTOML is a shortcut for c.ShouldBindWith(obj, binding.TOML).
+// It works like ShouldBindJSON but binds the request body as TOML data.
 func (c *Context) ShouldBindTOML(obj any) error {
 	return c.ShouldBindWith(obj, binding.TOML)
 }
 
 // ShouldBindPlain is a shortcut for c.ShouldBindWith(obj, binding.Plain).
+// It works like ShouldBindJSON but binds plain text data from the request body.
 func (c *Context) ShouldBindPlain(obj any) error {
 	return c.ShouldBindWith(obj, binding.Plain)
 }
 
 // ShouldBindHeader is a shortcut for c.ShouldBindWith(obj, binding.Header).
+// It works like ShouldBindJSON but binds values from HTTP headers.
 func (c *Context) ShouldBindHeader(obj any) error {
 	return c.ShouldBindWith(obj, binding.Header)
 }
 
 // ShouldBindUri binds the passed struct pointer using the specified binding engine.
+// It works like ShouldBindJSON but binds parameters from the URI.
 func (c *Context) ShouldBindUri(obj any) error {
 	m := make(map[string][]string, len(c.Params))
 	for _, v := range c.Params {