Add more info on the "Depth Graph" feature in the User's Guide

This is currently the only page discussing the feature: https://wiki.transvar.org/display/igbman/Creating+Graph+Tracks+from+Annotation+Tracks

We need more pertinent info in the Depth Graph section such as the differences between Depth Graph (All) and Depth Graph (Start).

Still need to update the screenshot to include a better image and need to verify that the page is the way the rest of the team wants it to be.

This issue still needs editing, waiting for feedback from Ann.

Before closing this issue I need to make sure to follows Ann's comments above and to also replace the mismatch graph image, but first I need to figure out why tooltips are not working for graph tracks.

I've updated the "Creating graph tracks from annotation tracks" page within the User's Guide. Specifically, I:

• Added an image to the Introduction depicting how to create each of the graphs
• Updated the outdated Mismatch Graph picture
• Created a more concise description of Mismatch Pileup Graphs

Dr. Freese reviewed this ticket and the updated page in the User's Guide. All looks good. Closing this ticket.