Update README.md

[abdullahkavakli]

description was need for "view on github button" You can add this: github: is_project_page: ["true" or "false" to indicate whether to add "view on github button] I also edited .rubocop.yml by the explanation here: https://github.com/pages-themes/slate/issues/60#issuecomment-811567432

[welcome[bot]]

Welcome! Congrats on your first pull request to the Slate theme. If you haven't already, please be sure to check out the contributing guidelines.

[rafalkrupinski]

why do you keep including changes to rubocop file?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.