Add raspberry pi docs (#1252)

book/src/SUMMARY.md

@@ -6,6 +6,7 @@
     * [Building from Source](./become-a-validator-source.md)
 * [Installation](./installation.md)
     * [Docker](./docker.md)
+    * [Raspberry Pi 4](./pi.md)
 * [Key Management](./key-managment.md)
     * [Create a wallet](./wallet-create.md)
     * [Create a validator](./validator-create.md)

book/src/installation.md

@@ -26,7 +26,16 @@ If this doesn't work or is not clear enough, see the [Detailed Instructions](#de
 
 ## Troubleshooting
 
-###  Command is not found
+### Dependencies (Ubuntu)
+
+Several dependencies may be required to compile Lighthouse. The following
+packages may be required in addition a base Ubuntu Server installation:
+
+```bash
+sudo apt install -y git gcc g++ make cmake pkg-config libssl-dev
+```
+
+### Command is not found
 
 Lighthouse will be installed to `CARGO_HOME` or `$HOME/.cargo`. This directory
 needs to be on your `PATH` before you can run `$ lighthouse`.

book/src/pi.md

@@ -0,0 +1,53 @@
+# Raspberry Pi 4 Installation
+
+Tested on:
+
+ - Raspberry Pi 4 Model B (4GB)
+ - `Ubuntu 20.04 LTS (GNU/Linux 5.4.0-1011-raspi aarch64)`
+
+### 1. Install Ubuntu
+
+Follow the [Ubuntu Raspberry Pi installation instructions](https://ubuntu.com/download/raspberry-pi).
+
+**A 64-bit version is required** and latest version is recommended (Ubuntu
+20.04 LTS was the latest at the time of writing).
+
+A graphical environment is not required in order to use Lighthouse.  Only the
+terminal and an Internet connection are necessary.
+
+### 2. Install Packages
+
+Install the [Ubuntu Dependencies](installation.md#dependencies-ubuntu).
+(I.e., run the `sudo apt install ...` command at that link).
+
+> Tips:
+>
+> - If there are difficulties, try updating the package manager with `sudo apt
+>   update`.
+
+### 3. Install Rust
+
+Install Rust as per [rustup](https://rustup.rs/). (I.e., run the `curl ... `
+command).
+
+> Tips:
+>
+> - When prompted, enter `1` for the default installation.
+> - Try running `cargo version` after Rust installation completes. If it cannot
+>   be found, run `source $HOME/.cargo/env`.
+> - It's generally advised to append `source $HOME/.cargo/env` to `~/.bashrc`.
+
+### 4. Install Lighthouse
+
+```bash
+git clone https://github.com/sigp/lighthouse.git
+cd lighthouse
+make
+```
+
+Compiling Lighthouse can take up to an hour. The safety guarantees provided by
+the Rust language unfortunately result in a lengthy compilation time on a
+low-spec CPU like a Raspberry Pi.
+
+Once installation has finished, confirm Lighthouse is installed by viewing the
+usage instructions with  `lighthouse --help`.