expand arm64 into a more friendly document

docs/contributing/building-arm64.md

@@ -0,0 +1,47 @@
+# Building Desktop for `arm64`
+
+Desktop can be built and run on `arm64` (`aarch64`) hardware such as a Raspberry
+Pi 3.
+
+## Requirements
+
+In order to build for `arm64`, you will need the following:
+
+* A computer with a 64-bit ARMv8 processor.
+* A 64-bit OS.  You can use [Ubuntu 16.04](#ubuntu-1604) and then follow the
+instructions on setup there.
+
+## Setup
+
+Once you have the required tools installed, run this script to install the
+dependencies that Desktop needs for `arm64`:
+
+```shellsession
+$ script/install-arm64-deps.sh
+```
+
+**Note:** Do not use `yarn` here as there is no current way to set environment
+variables to rebuild native modules against `arm64`.
+
+Ensure you set the `TARGET_ARCH` environment variable in your shell:
+
+```shellsession
+$ export TARGET_ARCH=arm64
+```
+
+## Building
+
+After that, you should be able to build the development version of Desktop:
+
+```shellsession
+$ yarn build:dev
+$ yarn start
+```
+
+Or if you want to test the production build:
+
+
+```shellsession
+$ yarn build:prod
+$ yarn start:prod
+```

docs/contributing/setup-arm64.md

@@ -1,15 +0,0 @@
-# Setting Up Development Dependencies on ARM64
-
-Desktop can be built and run on arm64 (aarch64) hardware such as a Raspberry Pi 3.
-In order to build for arm64, you will need the following:
-
-* A computer with a 64-bit ARMv8 processor.
-* A 64-bit OS.  You can use [Ubuntu 16.04](#ubuntu-1604) and then follow the instructions
-on setup there.
-* Instead of running `yarn` to get all required dependencies on your machine, you will
-instead need to run `script/install-arm64-deps.sh`.
-* Before building with `yarn build:dev` or `yarn build:prod`, you will need to
-set the environment variable `TARGET_ARCH` to `arm64` eg:
-```shellsession
-export TARGET_ARCH=arm64
-```