Find regulation by citation

[carodew]

When I already know the regulation number I want, I want to be able to navigate to it quickly without having to scroll for a long time in the table of contents.

acceptance criteria

• Users should be able to find the correct regulation subpart faster than the currently available design allows (as evidenced by usability testing)
• Does not impair the ability of other users (who may not know the correct citation) to scan through the subpart titles or search by keyword