Update README for Components directory

[captainsafia]

Part of #27561.

[pranavkm]

What do you think about adding a general section to BuildFromSources.md that talks about how to build "sub-folders" and linking from here?

Each directory under src represents a feature area of ASP.NET Core. We provide convenience scripts build.sh or build.cmd inside these directories that let you build and test only this feature. For instance, if you were interested in contributing to Blazor, navigate to the src/Components directory, and run build.[cmd|sh] there to build all the projects and it's dependencies.

Then we link to these instructions from each of these docs. so we're not repeating ourselves?

[pranavkm]

This project takes a dependency on MVC and SignalR packages.

Ehh, these things are easy to go out of sync and don't really help the user much. Could we not list this here?

[captainsafia]

Then we link to these instructions from each of these docs. so we're not repeating ourselves?

Good insight. I think we can probably address this for all the projects in one go as part of #27631.

Ehh, these things are easy to go out of sync and don't really help the user much. Could we not list this here?

I've removed it.

[SteveSandersonMS]

Looks good to me! I'll assume you and @pranavkm will figure out the details of accounting for his feedback.

[ghost]

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