Respond to `/` key just like on github.com

[jsoref]

Code of Conduct

• I have read and agree to the GitHub Docs project's Code of Conduct

What article on docs.github.com is affected?

https://docs.github.com/

What changes are you suggesting?

Respond to users pressing / without focus in anything in particular in the same manner as on github.com:

https://docs.github.com/en

https://github.com/

Pressing / (on github.com):

Additional information

No response