docs: update for the new store structure

docs/concepts/state-management.md

@@ -73,8 +73,8 @@ src/app/core
               |  └─ index.ts
               ├─ bar
               |  └─ ...
-              ├─ foobar.state.ts
-              └─ foobar.system.ts
+              ├─ foobar-store.ts
+              └─ foobar-store.module.ts
 ```
 
 An application module named `foobar` with substates named `foo` and `bar` serves as an example.
@@ -93,12 +93,25 @@ Each substate should aggregate its store components in separate subfolders corre
 
 Furthermore, the state of foobar is aggregated in two files:
 
-- _foobar.state.ts_: Contains the `FoobarState` as an aggregate of the `foo` and `bar` states.
+- _foobar-store.ts_: Contains the `FoobarState` as an aggregate of the `foo` and `bar` states.
 
-- _foobar.system.ts_: Contains aggregations for `foobarReducers` and `foobarEffects` of the corresponding substates to be used in modules and `TestBed` declarations.
+- _foobar-store.module.ts_: Contains aggregations for `foobarReducers` and `foobarEffects` of the corresponding substates as well as the store module.
 
 Access to the state slice of `foobar` is provided with the `FoobarFacade` located in _foobar.facade.ts_
 
+## Core Store Structure
+
+The PWA has a core state initializing the [StoreModule.forRoot](https://ngrx.io/api/store/StoreModule#forroot) and multiple feature modules using [StoreModule.forFeature](https://ngrx.io/api/store/StoreModule#forfeature).
+
+- `core`: PWA runtime independent of the ICM like configuration, global error handling or [@ngrx/router-store](https://ngrx.io/guide/router-store) integration.
+- `shopping`: Logic and data for browsing the PWA independent of the current user.
+- `customer`: Everything user-related (anonymous or logged in) like the current basket or the user profile.
+- `content`: Everything related to the CMS.
+- `general`: Minor features that don't require a fully fledged feature store.
+- ...
+
+All store modules are aggregated and imported in the [`StateManagementModule`](../../src/app/core/state-management.module.ts).
+
 ## Naming
 
 Related to the example in the previous paragraph, we want to establish a particular naming scheme.

docs/guides/migrations.md

@@ -15,6 +15,27 @@ The old testing mechanism will be removed in version 0.23.
 
 We introduced a way to do [shallow testing with feature toggles](../concepts/configuration.md#unit-testing-with-feature-toggles) and used it in the tests.
 
+We [reorganized the core store](../concepts/state-management.md#core-store-structure):
+
+- new `customer`
+  - store/addresses => store/**customer**/addresses
+  - store/checkout/basket => store/**customer**/basket
+  - store/orders => store/**customer**/orders
+  - store/restore => store/**customer**/restore
+  - store/user => store/**customer**/user
+- new `core`
+  - store/configuration => store/**core**/configuration
+  - store/error => store/**core**/error
+  - store/messages => store/**core**/messages
+  - store/router => store/**core**/router
+  - store/viewconf => store/**core**/viewconf
+- new `general`
+  - store/contact => store/**general**/contact
+  - store/countries => store/**general**/countries
+  - store/regions => store/**general**/regions
+
+TSLint rules are set up to automatically fix imports, so run `npm run check` after upgrading.
+
 ## 0.19.1 to 0.20
 
 We upgraded from Angular 8 to version 9 and activated the new rendering engine Ivy with this (following the [official upgrade guide](https://update.angular.io/#8.0:9.0l3)).