Refactor docs into mdbook (#547)

* Refactor documentation, ef_tests makefile

* Add makefile to root

* Tidy readme

* Fix readme badges

* Tidy logs

* Add terminalize gif

* Update readme image

* Update readme image

* Tidy logs

* Update readme image

* Update readme

* Update readme

* Fix book link

* Update makefiles

* Update book

* Fix link in book

* Add readme for book

* Remove old docs, move api spec YAML

* Fix eth2/ dir readme

* Add readme for lcli

* Add about this book section

* Minor formatting improvements

* Address mehdi's comments

book/src/contributing.md

@@ -0,0 +1,118 @@
+# Contributing to Lighthouse
+
+[![Chat Badge]][Chat Link]
+
+[Chat Badge]: https://img.shields.io/badge/chat-discord-%237289da
+[Chat Link]: https://discord.gg/cyAszAh
+
+
+Lighthouse welcomes contributions. If you are interested in contributing to the
+Ethereum ecosystem, and you want to learn Rust, Lighthouse is a great project
+to work on.
+
+To start contributing,
+
+1. Setup a [development environment](./setup.md).
+2. Browse through the [open issues](https://github.com/sigp/lighthouse/issues)
+   (tip: look for the [good first
+   issue](https://github.com/sigp/lighthouse/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
+   tag).
+3. Comment on an issue before starting work.
+4. Share your work via a pull-request.
+
+If you have questions, please reach out via
+[Discord](https://discord.gg/cyAszAh).
+
+## Ethereum 2.0
+
+Lighthouse is an implementation of the Ethereum 2.0 specification, as defined
+in the  [ethereum/eth2.0-specs](https://github.com/ethereum/eth2.0-specs)
+repository.
+
+We recommend reading Danny Ryan's (incomplete) [Phase 0 for
+Humans](https://notes.ethereum.org/@djrtwo/Bkn3zpwxB?type=view) before diving
+into the canonical spec.
+
+## Rust
+
+Lighthouse adheres to Rust code conventions as outlined in the [**Rust
+Styleguide**](https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/guide.md).
+
+Please use [clippy](https://github.com/rust-lang/rust-clippy) and
+[rustfmt](https://github.com/rust-lang/rustfmt) to detect common mistakes and
+inconsistent code formatting:
+
+```bash
+$ cargo clippy --all
+$ cargo fmt --all --check
+```
+
+### Panics
+
+Generally, **panics should be avoided at all costs**. Lighthouse operates in an
+adversarial environment (the Internet) and it's a severe vulnerability if
+people on the Internet can cause Lighthouse to crash via a panic.
+
+Always prefer returning a `Result` or `Option` over causing a panic. For
+example, prefer `array.get(1)?` over `array[1]`.
+
+If you know there won't be a panic but can't express that to the compiler,
+use `.expect("Helpful message")` instead of `.unwrap()`. Always provide
+detailed reasoning in a nearby comment when making assumptions about panics.
+
+### TODOs
+
+All `TODO` statements should be accompanied by a GitHub issue.
+
+```rust
+pub fn my_function(&mut self, _something &[u8]) -> Result<String, Error> {
+  // TODO: something_here
+  // https://github.com/sigp/lighthouse/issues/XX
+}
+```
+
+### Comments
+
+**General Comments**
+
+* Prefer line (``//``) comments to block comments (``/* ... */``)
+* Comments can appear on the line prior to the item or after a trailing space.
+```rust
+// Comment for this struct
+struct Lighthouse {}
+fn make_blockchain() {} // A comment on the same line after a space
+```
+
+**Doc Comments**
+
+* The ``///`` is used to generate comments for Docs.
+* The comments should come before attributes.
+
+```rust
+/// Stores the core configuration for this Lighthouse instance.
+/// This struct is general, other components may implement more
+/// specialized config structs.
+#[derive(Clone)]
+pub struct LighthouseConfig {
+    pub data_dir: PathBuf,
+    pub p2p_listen_port: u16,
+}
+```
+
+### Rust Resources
+
+Rust is an extremely powerful, low-level programming language that provides
+freedom and performance to create powerful projects. The [Rust
+Book](https://doc.rust-lang.org/stable/book/) provides insight into the Rust
+language and some of the coding style to follow (As well as acting as a great
+introduction and tutorial for the language).
+
+Rust has a steep learning curve, but there are many resources to help. We
+suggest:
+
+* [Rust Book](https://doc.rust-lang.org/stable/book/)
+* [Rust by example](https://doc.rust-lang.org/stable/rust-by-example/)
+* [Learning Rust With Entirely Too Many Linked Lists](http://cglab.ca/~abeinges/blah/too-many-lists/book/)
+* [Rustlings](https://github.com/rustlings/rustlings)
+* [Rust Exercism](https://exercism.io/tracks/rust)
+* [Learn X in Y minutes - Rust](https://learnxinyminutes.com/docs/rust/)