Performing minor enhancements (#1)

[NeaSTDL]

The following minor enhancements need to be performed:

• Simplify reducer factory returned wrappers.

To have:

const { reducers } = createReduxManager({ entity: 'fruits' });
const { entitiesReducers } = reducers;
const { create, delete, update, addSelected, removeSelected } = entitiesReducers; 
// ...

Instead of:

const { reducers } = createReduxManager({ entity: 'fruits' });
const { entitiesReducers } = reducers;
const { fruits: { create, delete, update, addSelected, removeSelected } } = entitiesReducers;
// ...

• Perform maintenance to test groups to divide them where necessary.
• Write documentation for code's functions.

[NeaSTDL]

Issue addressed into PR #12 . Closing issue.