Add some more read doc like before for dev

[1009058470]

What feature or change would you like to see made?

Is there any render pipeline and example for dev to understand how this work?

Why should we prioritize this feature?

because it is import for other dev who are instersting on this can read and make some change for this repo

[sedghi]

we tried our best here, https://www.cornerstonejs.org/docs/category/concepts