Add accessibility resources page

[cjrace]

Overview of changes

Add a new accessibility tools and guidance page in the learning resources section

Why are these changes being made?

Request by an analyst for a list of free tools to get started with, expanded into making this page so it's available for everyone and we can build it up over time too.

Detailed description of changes

1. New accessibility resources page
2. Updated renv snapshot to latest R version
3. Fix broken link to RAP pages from SQL page

Issue ticket number/s and link

Fixes #54

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

[cjrace]

Add quick notes for free accessibility tools and checking to analysts guide