docs(v2): blog.md with docs: false, for blog-only mode

[Romstar]

Added docs: false, to the config for blog-only mode because we do not want any documents if we're in blog-only mode otherwise, we probably wouldn't use blog-only mode.

Motivation

To setup only a blog with Docusaurs v2.

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Yes

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Related PRs

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[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	89
🟢 Accessibility	99
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-3931--docusaurus-2.netlify.app/classic/

[github-actions]

Size Change: +20 B (0%)

Total Size: 152 kB

ℹ️ View Unchanged

Filename	Size	Change
website/build/blog/2017/12/14/introducing-docusaurus/index.html	20.7 kB	+1 B
website/build/docs/introduction/index.html	180 B	0 B
website/build/index.html	5.8 kB	-1 B
website/build/main.********.js	108 kB	+20 B (0%)
website/build/styles.********.css	17.6 kB	0 B

_{compressed-size-action}

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[slorber]

Thanks