Update ssh config instructions for berlin

[ivirshup]

I'm helping a colleague set up their ssh config and they got confused about which fields were supposed to be replaced in the ssh config. I remembered being confused about this when I set it up, so I figured the instructions could be more explicit.

Open to doing something different, but figured {curly braces} may be the most familiar signal for "to replace"

Try to fulfill the following points before the Pull Request is merged:

• Please create your prs against the dev branch
• Please WAIT for the tests to finish.
• All tests have been successfully completed.
• When adding a new documentation or tutorial, make sure that the markdown is linked in the config.yml