Add option for meta description

[namanlp]

🚀 Feature Proposal

Currently, It is unfeasible to change SEO descriptions of each individual pages, like meta description, og:description etc.

Motivation

Description of each page is very necessary for SEO.

Example

For example, pages like

https://smooth-doc.com/docs/write-mdx/
https://smooth-doc.com/docs/components/button/
etc.

may need separate description than "Ready to use documentation theme for Gatsby"

Pitch

It is very important for Smooth DOC, as it is necessary for any document website to be good at SEO with precise meta descriptions of each page.