Remove incorrect comments about context.Bind() and improve docs (#3028)

context.go

@@ -601,11 +601,10 @@ func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string) error
 	return err
 }
 
-// Bind checks the Content-Type to select a binding engine automatically,
-// Depending on the "Content-Type" header different bindings are used:
+// Bind checks the Method and Content-Type to select a binding engine automatically,
+// Depending on the "Content-Type" header different bindings are used, for example:
 //     "application/json" --> JSON binding
 //     "application/xml"  --> XML binding
-// otherwise --> returns an error.
 // It parses the request's body as JSON if Content-Type == "application/json" using JSON or XML as a JSON input.
 // It decodes the json payload into the struct specified as a pointer.
 // It writes a 400 error and sets Content-Type header "text/plain" in the response if input is not valid.
@@ -660,14 +659,13 @@ func (c *Context) MustBindWith(obj interface{}, b binding.Binding) error {
 	return nil
 }
 
-// ShouldBind checks the Content-Type to select a binding engine automatically,
-// Depending on the "Content-Type" header different bindings are used:
+// ShouldBind checks the Method and Content-Type to select a binding engine automatically,
+// Depending on the "Content-Type" header different bindings are used, for example:
 //     "application/json" --> JSON binding
 //     "application/xml"  --> XML binding
-// otherwise --> returns an error
 // It parses the request's body as JSON if Content-Type == "application/json" using JSON or XML as a JSON input.
 // It decodes the json payload into the struct specified as a pointer.
-// Like c.Bind() but this method does not set the response status code to 400 and abort if the json is not valid.
+// Like c.Bind() but this method does not set the response status code to 400 or abort if input is not valid.
 func (c *Context) ShouldBind(obj interface{}) error {
 	b := binding.Default(c.Request.Method, c.ContentType())
 	return c.ShouldBindWith(obj, b)