Updated the documentation on using the plugins (#2553)

Co-authored-by: Andrey Leybovich <andrey.leybovich@novartis.com>

docs/content/recipes/modelgen-hook.md

@@ -16,7 +16,13 @@ the generated data structure.
 First of all, we need to create a function that will mutate the generated model.
 Then we can attach the function to the plugin and use it like any other plugin.
 
+Create `generate.go` file in the same folder as `resolver.go` (usually in `graph` folder) and add the following code:
+
 ```go
+//go:build ignore
+
+package main
+
 import (
 	"fmt"
 	"os"
@@ -58,6 +64,10 @@ func main() {
 }
 ```
 
+In `resolver.go`, add `//go:generate go run generate.go` (or replace `//go:generate go run github.com/99designs/gqlgen generate` if you have it there). 
+
+Now you can run `go generate ./...` to generate the code.
+
 Now fields from generated models will contain a additional tag `orm_binding`.
 
 This schema:

docs/content/reference/plugins.md

@@ -10,8 +10,10 @@ default plugins you will need to create your own entrypoint:
 
 ## Using a plugin
 
+To use a plugin during code generation, you need to create a new entry point. Create `generate.go` in the same folder as `resolver.go` with the following code:
+
 ```go
-// +build ignore
+// go:build ignore
 
 package main
 
@@ -47,6 +49,8 @@ func main() {
 
 ```
 
+In `resolver.go`, add `//go:generate go run generate.go`. Now you can run `go generate ./...` instead of `go run github.com/99designs/gqlgen generate` to generate the code.
+
 ## Writing a plugin
 
 There are currently only two hooks: