update some instructions for workflow changes in YarnSpinner-Godot 0.2.0

[dogboydog]

Replace #39

Sorry, I am clumsy and deleted a bunch of repositories yesterday that I thought were unused, one of which was called YarnDonutDocs. I thought that was only used when I was going to create a separate GitBook instance, but it turns out that was the repo used in the beginner's guide PR.

Starting on the changes for updating the beginner's guide for the changes in YarnSpinner-Godot 0.2.0

• [x] Instructions for creating .yarnprojects and .yarn scripts
• [x] Update screenshots - I might be able to replicate the style of the existing screenshots with my spare Mac machine. The screenshots that need to be updated have their description updated in this branch. Edit: attached screenshots, but I didn't update the links in this branch yet. If you'd like me to let me know.
• [ ] Address any questions or feedback

Merge after https://github.com/YarnSpinnerTool/YarnSpinner-Godot/pull/28

Let me know any requests to help with further doc updates for these changes -whether updating some other doc files or just answering questions about how the plugin works. Thanks

Screenshots in #39

[dogboydog]

I think the last item to update YarnSpinner-Godot to 0.2.0 is to get the beginner's guide updated to use the new workflow using .yarnproject files. I don't plan any more code changes to that PR, but the beginner's guide will be wrong until it's updated. Tried my hand at getting new screenshots and updating the instructions. Is there anything else I can do to help finish up this PR? @parisba

[dogboydog]

Merging to get the information updated at least and to check if the screenshots are working on the site. If the screenshots are not working, I will try to fix them as soon as possible