Add shiny best practice

[christopherdias11]

Overview of changes

This adds more to the Learning R Shiny section.

Why are these changes being made?

As part of work in a Dashboards working group we are looking to promote consistent approaches to R Shiny dashboards across the DfE. This aims to give:

• Resources on getting started
• Best practice guidance
• Resources for more advanced Shiny techniques

Detailed description of changes

• Adding a section on different packages for rendering tables to learning-development/r.qmd

The following changes to writing-visualising/dashboards_rshiny.qmd:

• Added a section to Creating a user interface to advise people how to construct a template and to use bslib
• Section on R Shiny best practice giving a checklist of things a developer should strive to do in their project
• Section on using databases with R Shiny for optimal performance and security
• Section on Leveling up your shiny to give some more advanced techniques and reading material

To check:

• Links work
• You agree with the materials suggested
• Do you have any other suggestions on material/structure?

Issue ticket number/s and link

Issue #112

Checklist before requesting a review

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