Add script for checking broken links in website

[dimaMachina]

Is your feature request related to a problem? Please describe. guild-website has a nice script for verifying broken links

Describe the solution you'd like

• add the same script as we use in guild-website https://github.com/the-guild-org/the-guild-website/blob/master/check-links.ts
• adapt to graphql-tools if needed
• setup GitHub workflow to trigger check-links script

Describe alternatives you've considered

Additional context