Ubuntu setup - additional steps required to install homebrew

[maneesha]

In the Linux setup instructions, the first step is:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

A few things to note after this step that may be useful to include in the instructions:

1. This may require admin password
2. There are three commands listed in stdout that you must follow. This is what that looks like on my machine (my output explicitly defined my home dir; I've replaced that with ~ here):

==> Next steps:
- Run these three commands in your terminal to add Homebrew to your PATH:
    echo '# Set PATH, MANPATH, etc., for Homebrew.' >> ~/.bash_profile
    echo 'eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"' >> ~/.bash_profile
    eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"
- Install Homebrew's dependencies if you have sudo access:
    sudo apt-get install build-essential
  For more information, see:
    https://docs.brew.sh/Homebrew-on-Linux
- We recommend that you install GCC:
    brew install gcc
- Run brew help to get started