Updates dev env docs

* Removes mention of Python virtualenv as it comes by default with Python 3
* Updates macOS docs to make sure that steps work for Intel and ARM macs
* Markdown formatting fixes

docs/prepare-your-dev-environment.md

@@ -9,10 +9,7 @@ This document goes through the development dependencies one requires in order to
 
 1. Install [Python 3.6+](https://www.python.org/downloads), if you haven't already.  You will also need `python-setuptools` installed, if you don't have it installed already.
 
-1. Install `virtualenv`, a tool for managing Python virtual environments.
-> The package is called `python-virtualenv` on both Fedora and Debian-based systems.
-
-1. Install the [az client](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli), if you haven't already. You will need `az` version 2.0.72 or greater, as this version includes the `az network vnet subnet update --disable-private-link-service-network-policies` flag.
+1. Install the [az client](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli), if you haven't already.
 
 1. Install [OpenVPN](https://openvpn.net/community-downloads) if it is not already installed
 
@@ -21,54 +18,53 @@ This document goes through the development dependencies one requires in order to
 1. Install [Podman](https://podman.io/getting-started/installation) and [podman-docker](https://developers.redhat.com/blog/2019/02/21/podman-and-buildah-for-docker-users#) if you haven't already, used for building container images.
 
 1. Run for `az acr login` compatability
-```bash
-sudo touch /etc/containers/nodocker
-```
+    ```bash
+    sudo touch /etc/containers/nodocker
+    ```
 
 ### Fedora Packages
 1. Install the `gpgme-devel`, `libassuan-devel`, and `openssl` packages.
-> `sudo dnf install -y gpgme-devel libassuan-devel openssl`
+    > `sudo dnf install -y gpgme-devel libassuan-devel openssl`
 
 1. Install [Docker 17.05+](https://docs.docker.com/engine/install/fedora/) or later, used as an alternative to podman.
 
 ### Debian Packages
-1. Install the `libgpgme-dev` package.
+
+Install the `libgpgme-dev` package.
 
 ### MacOS Packages
+
 1. We are open to developers on MacOS working on this repository.  We are asking MacOS users to setup GNU utils on their machines.
 
-We are aiming to limit the amount of shell scripting, etc. in the repository, installing the GNU utils on MacOS will minimise the chances of unexpected differences in command line flags, usages, etc., and make it easier for everyone to ensure compatibility down the line.
+    We are aiming to limit the amount of shell scripting, etc. in the repository, installing the GNU utils on MacOS will minimise the chances of unexpected differences in command line flags, usages, etc., and make it easier for everyone to ensure compatibility down the line.
+
+    Install the following packages on MacOS:
+    ```bash
+    # GNU Utils
+    brew install coreutils findutils gnu-tar grep
 
-Install the following packages on MacOS:
-```bash
-# GNU Utils
-brew install coreutils
-brew install findutils
-brew install gnu-tar
-brew install grep
+    # Install envsubst (provided with gettext)
+    brew install gettext
+    brew link gettext
 
-# Install envsubst
-brew install gettext
-brew link --force gettext
+    # Install gpgme
+    brew install gpgme
+    ```
 
-# Install
-brew install gpgme
+1. Modify your `~/.zshrc` (or `~/.bashrc` for Bash): this prepends `PATH` with GNU Utils paths;
 
-# GNU utils
-# Ref: https://web.archive.org/web/20190704110904/https://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x
-# gawk, diffutils, gzip, screen, watch, git, rsync, wdiff
-export PATH="/usr/local/bin:$PATH"
-# coreutils
-export PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
-# findutils
-export PATH="/usr/local/opt/findutils/libexec/gnubin:$PATH"
+    ```bash
+    echo "export PATH=$(find $(brew --prefix)/opt -type d -follow -name gnubin -print | paste -s -d ':' -):\$PATH" >> ~/.zshrc
+    ```
 
-#grep
-export PATH="/usr/local/opt/grep/libexec/gnubin:$PATH"
+1. Add the following into your `~/.zshrc`/`~/.bashrc` file:
 
-#python-virtualenv
-sudo pip3 install virtualenv
-```
+    ```bash
+    export LDFLAGS="-L$(brew --prefix)/lib"
+    export CFLAGS="-I$(brew --prefix)/include"
+    export CGO_LDFLAGS=$LDFLAGS
+    export CGO_CFLAGS=$CFLAGS
+    ```
 
 ## Getting Started
 1. Login to Azure:
@@ -84,9 +80,8 @@ sudo pip3 install virtualenv
     ```bash
     git clone https://github.com/Azure/ARO-RP.git $GOPATH/src/github.com/Azure/ARO-RP
     ```
-    
+
 1. Go to project:
     ```bash
     cd ${GOPATH:-$HOME/go}/src/github.com/Azure/ARO-RP
     ```
-