Add mapping in r tips

[cjrace]

Overview of changes

Adding some notes on making maps in R that I started when editing the map app.

Why are these changes being made?

Might be helpful for analysts to shortcut the initial learning process and have some handy immediate references to start from.

Detailed description of changes

Added a variety of notes on mapping in R, an example interactive map in Shiny and tips for improving the load times of interactive maps.

There's definitely more information that could be added, though for now I figured I'd add the notes I had off the top of my head and we can always expand on demand.

I also renamed the project file as it's been bugging me I forgot to do it when we first moved over from the statisticians guide repo.

Issue ticket number/s and link

No related issues.

Checklist before requesting a review

• I have checked the contributing guidelines
• I have checked for and linked any relevant issues that this may resolve
• I have checked that these changes build locally (checking this now)
• I understand that if merged into main, these changes will be publicly available

[cjrace]

Tidy up and PR notes for making maps in R

[jen-machin]

Probably nitpicky comments and one entirely pointless one