Docs: Adding Organizations and Lagoonizing docs + reorganization

[AlannaBurke]

There's a lot in here!

• Re organizing of docs into Basic Concepts, Advanced Concepts, Using Lagoon - Basics, Using Lagoon - Advanced, Interacting with Lagoon, Lagoonizing
• Adding organization docs
• Adding Lagoonizing docs
• LOTS of minor updates

Please take a look at the docs overall and check for anything out of date or inaccurate.

General Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for inclusion in changelog

[tobybellwood]

This looks really cool @AlannaBurke - I've pushed a few commits:

1. Adds more redirects in, in case anyone has bookmarked the current docs, and we go and move the page
2. Fixed up a couple of broken refs 🧹
3. Whilst I was there, I updated the available image versions
4. Added an exeample menu re-jig - I haven't moved any files/folders - only the menu order
   a. Shorted the first two items (Concepts) to make them fit in the sidebar
   b. Moved Lagoonizing between Concepts and Using to break them up (and logical order)
   c. Moved images and applications under Lagoonizing
   d. Moved Logs under Interacting
   

Happy to have it overridden/reverted etc