Guide - add ability to compare specific revisions

Please give a quick overview of your product feature request or feedback and note who in your org is affected by this issue 

In Guide, would like to be able to select any two revisions in the Revisions page for an article, and see the differences between them. Currently users can only see the changes to two consecutive revisions.

What problem do you see this solving? (1-2 sentences) 

When editing an article, Guide writers will save the article frequently. This results in a large number of entries in the Revisions page, making it very difficult to see a summary of all changes that were made to the article in a given time period. Being able to select specific revisions to compare would be massively useful to tracking an article's revision history.

When was the last time you were affected by this lack of functionality, or specific tool? What happened? How often does this problem occur and how does this impact your business? (3-4 sentences)

This problem happens on a daily basis. Without this feature, we are forced to write up our own notes for changes that were made. This would be a huge productivity boost.

Are you currently using a workaround to solve this problem? (If yes, please explain) (1-2 sentences)

Yes, we use other tools like Google Sheets and JIRA to keep track of the status of the articles we are working on, and note any important changes that were made or need to be made. It would be incredibly useful if the "paper trail" that Zendesk saves for user activity was more robust.

What would be your ideal solution to this problem? How would it work or function? (1-2 sentences)

In the list of revisions on the right side of the Revisions page, you would select two revisions, then click a "Compare" button, and then all cumulative changes from the older revision to the newer revision would be shown in the article.