Docs: Improve guides for contributing (#19575)

* Move style guides into contribute directory

* Move contribution guides into contribute directory

* Refactor CONTRIBUTING.md

* Clean up docs/README.md

* Update reference to style guide and minor formatting fixes

* Apply suggestions from code review

Co-Authored-By: gotjosh <josue.abreu@gmail.com>

* Update CONTRIBUTING.md

Co-Authored-By: gotjosh <josue.abreu@gmail.com>

contribute/style-guides/redux.md

@@ -0,0 +1,133 @@
+# Redux framework
+
+To reduce the amount of boilerplate code used to create a strongly typed redux solution with actions, action creators, reducers and tests we've introduced a small framework around Redux.
+
+`+` Much less boilerplate code
+`-` Non Redux standard api
+
+## New core functionality
+
+### actionCreatorFactory
+
+Used to create an action creator with the following signature
+
+```typescript
+{ type: string , (payload: T): {type: string; payload: T;} }
+```
+
+where the `type` string will be ensured to be unique and `T` is the type supplied to the factory.
+
+#### Example
+
+```typescript
+export const someAction = actionCreatorFactory<string>('SOME_ACTION').create();
+
+// later when dispatched
+someAction('this rocks!');
+```
+
+```typescript
+// best practices, always use an interface as type
+interface SomeAction {
+  data: string;
+}
+export const someAction = actionCreatorFactory<SomeAction>('SOME_ACTION').create();
+
+// later when dispatched
+someAction({ data: 'best practices' });
+```
+
+```typescript
+// declaring an action creator with a type string that has already been defined will throw
+export const someAction = actionCreatorFactory<string>('SOME_ACTION').create();
+export const theAction = actionCreatorFactory<string>('SOME_ACTION').create(); // will throw
+```
+
+### reducerFactory
+
+Fluent API used to create a reducer. (same as implementing the standard switch statement in Redux)
+
+#### Example
+
+```typescript
+interface ExampleReducerState {
+  data: string[];
+}
+
+const intialState: ExampleReducerState = { data: [] };
+
+export const someAction = actionCreatorFactory<string>('SOME_ACTION').create();
+export const otherAction = actionCreatorFactory<string[]>('Other_ACTION').create();
+
+export const exampleReducer = reducerFactory<ExampleReducerState>(intialState)
+  // addMapper is the function that ties an action creator to a state change
+  .addMapper({
+    // action creator to filter out which mapper to use
+    filter: someAction,
+    // mapper function where the state change occurs
+    mapper: (state, action) => ({ ...state, data: state.data.concat(action.payload) }),
+  })
+  // a developer can just chain addMapper functions until reducer is done
+  .addMapper({
+    filter: otherAction,
+    mapper: (state, action) => ({ ...state, data: action.payload }),
+  })
+  .create(); // this will return the reducer
+```
+
+#### Typing limitations
+
+There is a challenge left with the mapper function that I can not solve with TypeScript. The signature of a mapper is
+
+```typescript
+<State, Payload>(state: State, action: ActionOf<Payload>) => State;
+```
+
+If you would to return an object that is not of the state type like the following mapper
+
+```typescript
+mapper: (state, action) => ({ nonExistingProperty: ''}),
+```
+
+Then you would receive the following compile error
+
+```shell
+[ts] Property 'data' is missing in type '{ nonExistingProperty: string; }' but required in type 'ExampleReducerState'. [2741]
+```
+
+But if you return an object that is spreading state and add a non existing property type like the following mapper
+
+```typescript
+mapper: (state, action) => ({ ...state, nonExistingProperty: ''}),
+```
+
+Then you would not receive any compile error.
+
+If you want to make sure that never happens you can just supply the State type to the mapper callback like the following mapper:
+
+```typescript
+mapper: (state, action): ExampleReducerState => ({ ...state, nonExistingProperty: 'kalle' }),
+```
+
+Then you would receive the following compile error
+
+```shell
+[ts]
+Type '{ nonExistingProperty: string; data: string[]; }' is not assignable to type 'ExampleReducerState'.
+  Object literal may only specify known properties, and 'nonExistingProperty' does not exist in type 'ExampleReducerState'. [2322]
+```
+
+## New test functionality
+
+### reducerTester
+
+Fluent API that simplifies the testing of reducers
+
+#### Example
+
+```typescript
+reducerTester()
+  .givenReducer(someReducer, initialState)
+  .whenActionIsDispatched(someAction('reducer tests'))
+  .thenStateShouldEqual({ ...initialState, data: 'reducer tests' });
+```