[DOC]: Monorepo user guide and examples

[jrhemstad]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this bug and that I agree to the Code of Conduct

Is this for new documentation, or an update to existing docs?

New

Describe the incorrect/future/missing documentation

Users will want to know how they should use CCCL from the new monorepo. We should provide a guide linked from our README that shows various use cases. We should steer people towards using cmake and CPM whenever possible.

As an example, here's a similar doc I wrote for the stdexec repo: https://github.com/nvidia/stdexec#how-to-get-stdexec

Tasks

Beta Give feedback

1. Add a "How to get CCCL" section to README
2. Add a "Using CCCL" section to README
3. Create a CCCL demo project #131
   doc infrastructure +2
   

If this is a correction, please provide a link to the incorrect documentation. If this is a new documentation request, please link to where you have looked.

No response

[jrhemstad]

Closed by #291