rust webpack template tutorial

[DebugSteven]

This is a work in progress PR for the rust webpack template tutorial.

At the moment, I believe the workflow to use the template is filled in pretty well. There are empty WIP files to talk more about the generated src/lib.rs file & the web-sys dependency in the Cargo.toml, in addition to the other dependencies & crate type that are discussed in the npm-browser-packages template tutorial.

I'd appreciate feedback on content so far & possibly what to do about duplication across tutorials, if that's a priority.

[danwilhelm]

If you'd like to save some time writing the deep dives, the Cargo.toml and lib.rs auto-generated by npm init rust-webpack are extremely similar to those described in the existing deep dives here: https://github.com/rustwasm/wasm-pack/tree/master/docs/src/tutorial/template-deep-dive

[DebugSteven]

Hey @xtuc this PR is ready for review. I'm happy to make changes based on any feedback. Thanks for offering to look this over.

[xtuc]

This isn't needed, Webpack's wasm-pack-plugin will spawn wasm-pack. Only npm start or npm run build in the root directory is needed.

[DebugSteven]

Thank you for explaining that! I pushed up a change that I think reflects that a little better in the docs now.

[ashleygwilliams]

@DebugSteven is this ready for review? Let me know! And thanks for all the effort! I'm excited for this to land :)

[DebugSteven]

@ashleygwilliams It's ready for review! Thanks for your patience.

[ashleygwilliams]

i'll probably try to consolidate some of the duplication before the next release but this is really great!! thank you so much for all your efforts here!! <3