fix(theme-algolia): declare content-docs as dependency

[Josh-Cena]

Motivation

This throws an error in pnp:

Module not found: Error: Can't resolve '@docusaurus/plugin-content-docs/client' in './.yarn/__virtual__/@docusaurus-theme-search-algolia-virtual-8b78fceaa5/0/cache/@docusaurus-theme-search-algolia-npm-2.0.0-beta.17-609067fadc-8a603d743a.zip/node_modules/@docusaurus/theme-search-algolia/lib/theme/SearchPage'

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

Sadly our E2E test doesn't cover the search function

[netlify]

✔️ [V2]

🔨 Explore the source changes: 4703c29

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[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	68
🟢 Accessibility	100
🟢 Best practices	92
🟢 SEO	100
🟢 PWA	90

Lighthouse ran on https://deploy-preview-6888--docusaurus-2.netlify.app/

[github-actions]

Size Change: 0 B

Total Size: 791 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	49.9 kB
website/build/assets/css/styles.********.css	105 kB
website/build/assets/js/main.********.js	597 kB
website/build/index.html	38.7 kB

_{compressed-size-action}

[Josh-Cena]

The error doesn't seem related—can be reproduced on master dating a few commits back as well. (Re-ran the actions of commits that used to pass.) To be debugged later.