fix(docs): add developer guide with setup

docs/dev.md

@@ -0,0 +1,76 @@
+# Developer Guide
+
+## Setup
+
+### Linux
+
+Install NodeSource repository and `node`:
+
+```shell
+> curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
+> sudo apt-get install -y nodejs
+```
+
+- https://github.com/nodesource/distributions/blob/master/README.md#installation-instructions
+
+Install yarnpkg repository and `yarn`:
+
+```shell
+> curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+> echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+> sudo apt update && sudo apt install yarn
+```
+
+- https://classic.yarnpkg.com/en/docs/install/#debian-stable
+
+### Mac OS
+
+Install `brew`:
+
+```shell
+> /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
+```
+
+- https://brew.sh/
+
+Install `make`, `node`, and `yarn`:
+
+```shell
+> brew install --with-default-names make
+> brew install node yarn
+```
+
+- https://www.gnu.org/software/make/
+- https://formulae.brew.sh/formula/node
+- https://classic.yarnpkg.com/en/docs/install/#mac-stable
+
+## Building
+
+Building the app is done through `make` and its targets. To see a list of available targets:
+
+```shell
+> make help
+
+Makefile:all                   builds, bundles, and tests the application
+Makefile:build                 builds, bundles, and tests the application
+Makefile:build-docs            generate html docs
+Makefile:build-image           build a docker image
+Makefile:clean                 clean up everything added by the default target
+Makefile:clean-deps            clean up the node_modules directory
+Makefile:clean-target          clean up the target directory
+...
+```
+
+### Compiling Typescript
+
+```shell
+> make
+# or
+> make ci
+```
+
+This will compile the code and run tests.
+
+### Running Mocha Tests
+
+Tests use Mocha: https://mochajs.org/#getting-started