doc: outline for development section

[kbvernon]

Here is a proposal for pages in the development section:

1. Project structure
2. extendr macros
3. The build cycle
4. Robj - R's universal SEXP
5. Data types, scalars, vectors, and missing values
6. R Lists
7. Rust structs and hashmaps
8. R attributes, names, and S3 classes
9. R data frames and matrices
10. Condition handling
11. External pointers

I want to suggest that we move examples of working with specific Rust crates like tokio into blog posts. Then we should introduce two new sections at the same level as "development" and "publishing," specifically "features" and "advanced topics." Features would include all the gated crate integrations like serde and faer, and advanced topics would be for stuff like metaprogramming.

What do you all think? We already have a lot of this content. It just needs to be cleaned up, organized, and updated to be consistent with extendr 0.9.0 and rextendr 0.5.0.

[JosiahParry]

"I want to suggest that we move examples of working with specific Rust crates like tokio into blog posts."

I disagree a lot with this. These are foundational crates in the rust ecosystem that will be encountered time and time again. Having clearly documented patterns behooves us and the community. I would put tokio and arrow above faer in utility. Just because there isn't a "feature" for it doesn't mean that is shouldn't be documented similarly.

I agree that the structure should probably organized similarly to you've described. I think maybe, though, that I would put rust structured data, S3 related stuff before data.frames.

[kbvernon]

That makes sense! Instead of an extender-specific "features" section, maybe a more general section detailing how to integrate foundational rust crates into an extendr project would be more useful.