[DOCS] "How to create a custom component" tutorial in @daffodil/design

[xelaint]

📄 Documentation Request

What were you doing?

Trying to create my own custom component and didn't understand why or how daff-map-get is used.

Expected behavior

1. Tutorial on how to set up files to create your own custom component
2. Document usage of daff-map-get

Existing Documentation

None.

Environment

Daffodil version: X.Y.Z
Angular version: X.Y.Z 

 
For Tooling issues:
- Node version: XX  
- Platform:  

Others: