README.md out of date and incorrect on capgen branch

[gold2718]

Description

The README.md file on the feature/capgen branch is incorrect in that it discusses usage of the prebuild system.
This should be corrected to discuss usage using capgen.
Separately, the file claims that "This is the release v0.1.0 of the CCPP." which seems a bit out of date.

Steps to Reproduce

Read README.md

[climbfuji]

@gold2718 README.md has been updated in main and feature/capgen, they are now identical. Do you think this is sufficient to close this issue?

[climbfuji]

I think that the issue on updating the documentation for capgen #418 includes the top-level README.md.

[gold2718]

@climbfuji,

Thanks for working on this. I like the first part but have a couple of concerns about this bit:

The CCPP Single Column Model (SCM) is designed as a simple host model for testing and development of the CCPP; information about building and using the CCPP in this context can be found in the CCPP SCM Users Guide.

First, it is not made clear that the SCM is not located in this repository. I suggest including that information in the description. Second, I believe that the SCM is meant to be more than "a simple host model for testing and development of the CCPP". Rather, I think the description should be expanded. A suggestion for that section:

---

The CCPP Single Column Model (SCM, located at https://github.com/NCAR/ccpp-scm) is designed as a simple CCPP host model for hierarchical system testing and development of CCPP physics schemes and suites. Information about building and using the CCPP in this context can be found in the CCPP SCM Users Guide.

[climbfuji]

@gold2718 That sounds great, thanks for the suggestion. @mkavulich Do you want to take care of this or should I?