Create the Twiggy guide!

This just chops up the existing README.md and puts it into an mdbook.

Author: fitzgen

.gitignore

@@ -8,3 +8,4 @@ twiggy_wasm_api.d.ts
 twiggy_wasm_api.js
 twiggy_wasm_api.wasm
 twiggy_wasm_api_bg.wasm
+guide/book

CONTRIBUTING.md

@@ -1,148 +1,3 @@
 # Contributing to `twiggy`
 
-Hi! We'd love to have your contributions! If you want help or mentorship, reach
-out to us in a GitHub issue, or ping `fitzgen` in [`#rust-wasm` on
-`irc.mozilla.org`](irc://irc.mozilla.org#rust-wasm) and introduce yourself.
-
-<!-- START doctoc generated TOC please keep comment here to allow auto update -->
-<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
-
-
-- [Code of Conduct](#code-of-conduct)
-- [Building and Testing](#building-and-testing)
-  - [Building for the Native Target](#building-for-the-native-target)
-  - [Building for the `wasm32-unknown-unknown` Target](#building-for-the-wasm32-unknown-unknown-target)
-  - [Testing](#testing)
-    - [Authoring New Tests](#authoring-new-tests)
-    - [Updating Test Expectations](#updating-test-expectations)
-- [Automatic Code Formatting](#automatic-code-formatting)
-- [Pull Requests](#pull-requests)
-- [Contributions We Want](#contributions-we-want)
-- [Team](#team)
-
-<!-- END doctoc generated TOC please keep comment here to allow auto update -->
-
-## Code of Conduct
-
-We abide by the [Rust Code of Conduct][coc] and ask that you do as well.
-
-[coc]: https://www.rust-lang.org/en-US/conduct.html
-
-## Building and Testing
-
-### Building for the Native Target
-
-```
-$ cargo build --all --exclude twiggy-wasm-api
-```
-
-### Building for the `wasm32-unknown-unknown` Target
-
-```
-$ JOB=wasm ./ci/script.sh
-```
-
-### Testing
-
-```
-$ cargo test --all --exclude twiggy-wasm-api
-```
-
-#### Authoring New Tests
-
-Integration tests live in the `twiggy/tests` directory:
-
-```
-twiggy/tests
-├── expectations
-├── fixtures
-└── tests.rs
-```
-
-* The `twiggy/tests/tests.rs` file contains the `#[test]` definitions.
-
-* The `twiggy/tests/fixtures` directory contains input binaries for tests.
-
-* The `twiggy/tests/expectations` directory contains the expected output of test
-  commands.
-
-#### Updating Test Expectations
-
-To automatically update all test expectations, you can run the tests with the
-`TWIGGY_UPDATE_TEST_EXPECTATIONS=1` environment variable set. Make sure that you
-look at the changes before committing them, and that they match your intentions!
-
-## Automatic Code Formatting
-
-We use [`rustfmt`](https://github.com/rust-lang-nursery/rustfmt) to enforce a
-consistent code style across the whole code base.
-
-You can install the latest version of `rustfmt` with this command:
-
-```
-$ rustup update
-$ rustup component add rustfmt-preview
-```
-
-Ensure that `~/.rustup/toolchains/$YOUR_HOST_TARGET/bin/` is on your `$PATH`.
-
-Once that is taken care of, you can (re)format all code by running this command
-from the root of the repository:
-
-```
-$ cargo fmt --all
-```
-
-## Pull Requests
-
-All pull requests must be reviewed and approved of by at least one [team](#team)
-member before merging. See [Contributions We Want](#contributions-we-want) for
-details on what should be included in what kind of pull request.
-
-## Contributions We Want
-
-* **Bug fixes!** Include a regression test.
-
-* **Support for more binary formats!** See [this issue][more-formats] for
-  details.
-
-* **New analyses and queries!** Help expose information about monomorphizations
-  or inlining. Report diffs between two versions of the same binary. Etc...
-
-If you make two of these kinds of contributions, you should seriously consider
-joining our [team](#team)!
-
-Where we need help:
-
-* Issues labeled ["help wanted"][help-wanted] are issues where we could use a
-  little help from you.
-
-* Issues labeled ["mentored"][mentored] are issues that don't really involve any
-  more investigation, just implementation. We've outlined what needs to be done,
-  and a [team](#team) member has volunteered to help whoever claims the issue to
-  implement it, and get the implementation merged.
-
-* Issues labeled ["good first issue"][gfi] are issues where fixing them would be
-  a great introduction to the code base.
-
-[more-formats]: https://github.com/rustwasm/twiggy/issues/4
-[help-wanted]: https://github.com/rustwasm/twiggy/labels/help%20wanted
-[mentored]: https://github.com/rustwasm/twiggy/labels/mentored
-[gfi]: https://github.com/rustwasm/twiggy/labels/good%20first%20issue
-
-## Team
-
-| [<img alt="fitzgen" src="https://github.com/fitzgen.png" width="117">](https://github.com/fitzgen) | [<img alt="data-pup" src="https://github.com/data-pup.png" width="117">](https://github.com/data-pup) |
-|:---:|:---:|
-| [`fitzgen`](https://github.com/fitzgen) | [`data-pup`](https://github.com/data-pup) |
-
-Larger, more nuanced decisions about design, architecture, breaking changes,
-trade offs, etc are made by team consensus. In other words, decisions on things
-that aren't straightforward improvements or bug fixes to things that already
-exist in `twiggy`. If consensus can't be made, then `fitzgen` has the last
-word.
-
-**We need more team members!**
-[Drop a comment on this issue if you are interested in joining.][join]
-
-[join]: https://github.com/rustwasm/twiggy/issues/3
+[Read the "Contributing to Twiggy" section of the Twiggy guide!](https://rustwasm.github.io/twiggy/contributing/index.html)