Remove headings that say `<OS> ONLY`

[danman01]

This is unclear at times due to Mac OSX / Linux Only header size and / or indenting of sections underneath the headers.

We could:

• clean up the header size and indenting
• and / or: We could have a distinct symbol for linux only or mac only, and for everything else it could be assumed we run on all systems.
• or:
  We could separate the INSTALLFEST.md into two files, one for linux and one for mac.

[raq929]

We've considered the third option, and decided it doesn't make a whole lot of sense since a lot of the instructions are the same.

I like the idea of using symbols. 🐧 for linux? 😛
⛰ for mac? (That won't actually work, 'cause Sierra will go away.) Cleaning up the headers and indenting is also a good idea.

[raq929]

Related to #147

[MicFin]

Another example, this large Linux ONLY heading is misleading since it includes steps for OSX and LINUX directly beneath it.

Linux ONLY

Rbenv on Linux depends on another library called libffi-dev. Download and install it with the following command.

# LINUX ONLY
sudo apt-get install libffi-dev

1. Install Rbenv

   # OSX and LINUX
   brew install rbenv

2. Configure rbenv to use the correct directories:

   atom ~/.bashrc and paste in the following code BEFORE the stuff you pasted in about Git.

   # OSX and LINUX
   # Rbenv
   if which rbenv > /dev/null; then
    eval "$(rbenv init -)"
   fi

https://github.com/ga-wdi-boston/orientation/blob/master/INSTALLFEST.md#linux-only-2

[jrhorn424]

If there are no more specific fixes mentioned, I'd like to close this issue. It is too unfocused. Individual confusions should be noted in separate issues.

Please remove headings that say <OS> ONLY since that information should be noted inside a fenced code block as a comment.

[scottyscripts]

Issue no longer relevant with new structure of installfest on GHE