Fix images in Markdown kitchen sink

Changed small-image to match large image and fix reference

Renaming the large image and changed the index test references to display these images

Remote image here is not loading - https://just-the-docs.github.io/just-the-docs/docs/index-test/#large-image

via https://www.flickr.com/photos/97810305@N08/9401451269

[Security] Bump y18n from 3.2.1 to 3.2.2

Fix ol on index

Update readme

rename master -> main

Update to new repo path

Bumps [y18n](https://github.com/yargs/y18n) from 3.2.1 to 3.2.2. **This update includes a security fix.**
- [Release notes](https://github.com/yargs/y18n/releases)
- [Changelog](https://github.com/yargs/y18n/blob/master/CHANGELOG.md)
- [Commits](https://github.com/yargs/y18n/commits

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

v0.3.3

2019 replaced by 2020 in line 94.

Add custom header and footer include files

Bump stylelint-config-primer from 9.0.0 to 9.2.1

Limit the effect of `nav_exclude` to the main navigation

Bump stylelint from 13.6.1 to 13.7.2

Bump @primer/css from 15.1.0 to 15.2.0

Bump prettier from 2.1.1 to 2.1.2