docs(cookbook/dynamic_forms): fix a typo (#2857)

Author: JFrankfurt

public/docs/ts/latest/cookbook/dynamic-form.jade

@@ -42,7 +42,7 @@ include ../_util-fns
 
    In our example we will be using Reactive Forms. 
 
-   Reactive Forms belongs to a different `NgModule` called `ReactiveFormsModule`, so in order to access any Reactive Forms directives, we have to import `ReactiveFormsModule` from `AppModule`.    
+   Reactive Forms belongs to a different `NgModule` called `ReactiveFormsModule`, so in order to access any Reactive Forms directives, we have to import `ReactiveFormsModule` from the `@angular/forms` library.    
 
    We bootstrap our `AppModule` in main.ts.