link to episode's repo in feedback section

[regular]

should read

[gh icon] Found a typo or have a suggestion or question? [open an issue]() or [send a pull-request]() on [github]()!

Where

• gh-icon and github link to the episode's gh repo page.
• open an issue opens a popover that explains that discussions about improving an episode take place in gh issues and how to open a new issue
• send a pull request opens a popover that explains what a PR is and how to send one using the gh markdown editor.