Establish a simple convention for storing prompts/files that are used by the CLI, within each repo

(updated since we've come to a conclusion, in the comments)

As part of a few different workstreams (sample generation, readme generation) we've got some content that we expect each language will create, specific to them.

For instance, with sample generation, we'll have instructions about the C# guidelines that it should follow, local conventions and also the output format.

(Looking into this some more, the way to "bundle content that's not code into your assembly" is just to use .resx files, which can handle all kinds of media and have an established API)

- [ ] Create the resx file, add readme's templates to it
- [ ] Add this to the guidelines, in our azsdk-cli readme.