Add first version of cheatsheet file
user
```ruby
cheatsheet do
    title 'GitHub Desktop'
    docset_file_name 'GitHub_Desktop'
    keyword 'GitHub'
    source_url 'http://cheat.kapeli.com'

    category do
        id 'File'

        entry do
            name 'New Repository'
            command 'CMD+N'
        end

        entry do
            name 'New Branch'
            command 'CMD+SHIFT+N'
        end

        entry do
            name 'New Window'
            command 'CMD+ALT+N'
        end

        entry do
            name 'Clone Repository'
            command 'CMD+CTRL+O'
        end

        entry do
            name 'Add Local Repository'
            command 'CMD+O'
        end

        entry do
            name 'Close'
            command 'CMD+W'
        end
        
    end

  notes <<-'END'
    * Created by [Peter Blazejewicz](https://github.com/peterblazejewicz).
  END
end```
assistant