Fix link to styleguide in the documentation dir.
Created by: leehambley
Minor correction - it appears the website/STYLEGUIDE.md
in the github.com/sourcegraph/about repository was moved in https://github.com/sourcegraph/about/pull/19 (https://github.com/sourcegraph/about/commit/2ec613e0257d4ccaba01029879f81afb7a195ded#diff-ba2dc84c4bcbe54f368b6c7d3bc1b13e).
It looks like there is a check for some broken links in some circumstances in ./dev/check/*.sh
but not for this kind of defect.
Not sure where best to add a check for this, and in any case the request to curl -v https://sourcegraph.com/github.com/sourcegraph/about/-/blob/website/STYLEGUIDE.md
returns 200 HTTP/2 OK
so an automated check would be unlikely to catch this without upstream changes.