Document some macOS-specific steps needed to get the Ocim devstack working

[lgp171188]

Quoting @tinumide's feedback on the issues that she faced when trying to set up the devstack on macOS.

When I tried to run vagrant up, virtual box wouldn't load. Allowing oracle applications before running vagrant up fixed this for me. To allow oracle applications go to System Preferences > Security & Privacy and hit the allow button.
I couldn't run vagrant because my Xcode command line tools had been uninstalled. It is worth checking that Xcode command line tools are installed especially after a recent update. I'm not sure why an update would cause Xcode command line tools to be uninstalled in the first place.

[krisstern]

Hi, I would like to work on this issue, as I am just starting out exploring the OCIM Dev Stack on macOS.

[lgp171188]

@krisstern, you are welcome to work on this and contribute the relevant documentation changes.

FYI @antoviaque, @bradenmacdonald

[bradenmacdonald]

@krisstern @lgp171188 Please note that I don't want to spend any time on supporting the Vagrant dev environment for Ocim on MacOS or any platform. Please focus on improving the docker devstack instead. Eventually we can discontinue vagrant completely.