Create the E&J Citation index introduction page

[dorothyyeager]

User story
As an internal stakeholder or outside legal consultant, I need to see the explanation and justification for Commission regulations to do proper legal analysis of them.

Background: #2202, #2325, #2392, #2445, #2477, #2496, #2532, #2553, #2555

We completed the E&J citation index pages in the issues above. Now we need an index page to pull them all together and give users an access point.

Completion criteria:

• Turn https://transition.fec.gov/law/cfr/ej_citation.shtml into a Wagtail page.

[dorothyyeager]

I've started this page but have some design questions that I'll bring to design sync on Friday.

[dorothyyeager]

Thanks @JonellaCulmer for your suggestions - I think they did help! I'll send you a link to look over.

[dorothyyeager]

Members of the content team favored an approach where we treated the links to each page to appear in a consistent fashion. Making those last tweaks now.

[dorothyyeager]

The page is now live at https://www.fec.gov/legal-resources/regulations/explanations-and-justifications/explanations-and-justifications-citation-index/.

It has been linked off of the main E&J page (https://www.fec.gov/legal-resources/regulations/explanations-and-justifications/). Some text on that page was edited to remove references to the former paper-based format of the E&J compilation.

We're ready to close this part of the E&J issue. On to the chronological index! See #2569.