refactor: remove obsolete form components (#953)

BREAKING CHANGES: Our deprecated form components have been removed, use Formly to generate and maintain your forms. (see [Migrations / 1.4 to 2.0](https://github.com/intershop/intershop-pwa/blob/develop/docs/guides/migrations.md#14-to-20) for more details.

docs/guides/forms.md

@@ -33,7 +33,6 @@ If you are looking for documentation, refer to [older documentation](https://git
 
 - Reusable form components are available as Formly field types that come with wrappers and extensions. You can find them in: _app/shared/formly/_ or _app/shared/formly-address-forms/components_
 - These forms can be used as (sub)forms on arbitrary pages, e.g., there are address forms on registration page, checkout and _My Account_ pages.
-- There are still some deprecated form components which you can find in _app/shared/forms/components/\<form-name>_ or _app/shared/address-forms/components/\<form-name>_
 
 ### Page Specific Form Components
 

docs/guides/migrations.md

@@ -19,6 +19,11 @@ In projects where the recommended procedure for using a custom theme has been fo
 
 We moved the model `SelectOption` from the select.component.ts to the select-option.model.ts and adapted all necessary imports.
 
+In the PWA 0.28 we introduced the usage of [Formly](https://formly.dev/) to generate and maintain our forms.
+Now we removed the obsolete form components.
+If you want to use the obsolete form components in your project nevertheless, skip the commit `remove obsolete form components`.
+For more information concerning Formly please refer to our [Formly - Guide](./formly.md)).
+
 ## 1.1 to 1.2
 
 The `dist` folder now only contains results of the build process (except for `healthcheck.js`).