Add a link to repository path for CSC Quick Reference

[joonas-somero]

Proposed changes

The README file for CSC Quick Reference gets rendered as a page, so it's probably useful to have a link to the corresponding path in the repository on it. Preview of the page in question.

Checklist before requesting a review

• [x] I have followed the instructions in the Contributing and Styleguide documents.
• [x] My pull request passes the automated tests. (If not, visit pull requests at Travis CI and have a look at the job log.)
• [x] I have included a link to the appropriate preview page (select your branch from the list).