fix(content-blog): generate feed by reading build output

[Josh-Cena]

Motivation

Fix #5664
Fix #6195

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

The build output now shows all posts' content, including those with MDX.

[netlify]

✔️ [V2]

🔨 Explore the source changes: b789d2e

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/61f154f5ff418b00077c78ea

😎 Browse the preview: https://deploy-preview-6454--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🔴 Performance	47
🟢 Accessibility	100
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	92

Lighthouse ran on https://deploy-preview-6454--docusaurus-2.netlify.app/

[github-actions]

Size Change: +5.27 kB (+1%)

Total Size: 715 kB

Filename	Size	Change
website/.docusaurus/globalData.json	45.1 kB	+1.04 kB (+2%)
website/build/assets/css/styles.********.css	104 kB	+682 B (+1%)
website/build/assets/js/main.********.js	536 kB	+3.55 kB (+1%)

ℹ️ View Unchanged

Filename	Size
website/build/index.html	29.8 kB

_{compressed-size-action}

[github-actions]

Size Change: 0 B

Total Size: 710 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	44 kB
website/build/assets/css/styles.********.css	104 kB
website/build/assets/js/main.********.js	532 kB
website/build/index.html	29.8 kB

_{compressed-size-action}

[slorber]

Thanks, that looks like a nice fix overall, just a few minor changes

I can confirm in Feedly it's working fine, and relative images are not displayed properly 👍

[slorber]

LGTM thanks 👍