Migrate website to use the Docsy theme

[chalin]

This issue is to track the completion of the work started by @DarikshaAnsari as part of her Linux mentorship (LFX) during term 2.

Track progress via

• Branch: docsy
• Preview: https://docsy--in-toto.netlify.app
• Issue list: docsy

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Related and/or possible followup items:

• Reorganize the content of this repo so that it can be published directly on the website friends#39
• [docsy] Consider hosting a version of the spec directly on the website #72
• [docsy] Keep things DRY - avoid copy-pasted content from other repos #75

[chalin]

For reference to the pre-Docsy site, I've created the following:

• pre-docsy-2024 branch
• Branch preview at https://pre-docsy-2024--in-toto.netlify.app, showing the pre-Docsy-migration state of the website

[chalin]

@DarikshaAnsari - the new Docsy-based website is live! 🎉

[chalin]

For followup tasks, see:

• Docsy-migration followup #87