Create Glossary and add meta descriptions

[capjamesg]

This PR copies the language from the glossaries of the two papers listed below to form the basis of a Glossary page.

This page was suggested in Issue #1 and this contribution was made in response to a discussion with @mtom55.

This PR provides HTML IDs for each section on the glossary page, making it easy to link to each asset.

We might want to consider breaking out definitions into different pages should the glossary get sufficiently long.

• https://open-web-advocacy.org/files/OWA%20-%20Bringing%20Competition%20to%20Walled%20Gardens%20-%20v1.0.pdf
• https://open-web-advocacy.org/files/OWA%20-%20In-App%20Browsers%20-%20Subverting%20Competition,%20User%20Privacy%20&%20Choice%20-%20v1.1.pdf

This PR also adds meta descriptions to pages without them.

[aliblackwell]

This looks good @capjamesg, turns out permalinks require a slash at the end, otherwise the built page gets called glossary rather than glossary.html 🤷

I also deleted the duplicate sitemap.njk and robots.njk files at the website root which re-appeared in a previous commit.

Netlify build previews will help us resolve issues like this.

Was there a reason the page didn't get put in a nav? We could add it to the footer nav by editing /src/_data/navigation.json. I only didn't in case there was a reason you didn't want to make it public yet.

[thescientist13]

Just wanted to share now @capjamesg that if you basically make any update to this branch (and / or felt like updating with main branch), the new Deploy Previews I just setup should run and then we should be able to get a nice preview URL of your work to see and share. 🌟

[ssddanbrown]

All looked great to me!

Have now merged and followed it up with 3e410ec and cbd0064 to implement @aliblackwell's suggestion of adding a link to the footer, in addition to some minor punctuation alignment changes.