Update wasm-pack tutorial paths #154

[jrichocean]

Link to old issue

This issue was opened by @mgattozzi

We're just waiting for a 0.2 release of wasm-pack right now for this issue. In https://github.com/rust-lang-nursery/rust-wasm/pull/151 we changed a path reference from ./node_modules/@MYSCOPE/wasm-add/wasm_add.js to @MYSCOPE/wasm-add/wasm_add.js. As was noted in #151 after ashleygwilliams/wasm-pack#94 is closed we can shorten this further to @MYSCOPE/wasm-add which is more idiomatic for JS.

Mentoring instructions:

1. In src/wasm-pack/run-the-code.md change the import statement of index.js to the above statement.
2. Test that the changes work as part of the tutorial with the new syntax

[fitzgen]

The wasm-pack tutorial moved into the wasm-pack repo, please refile this issue there if it is still relevant.