(This commit contains binary images. Is that fine?)
+ Updated Timeline_docker image.
+ Added new Timeline_insertkeys image.
+ Added brief intro to the Timeline Docker before the overview "map" image and legend.
+ Fleshed out edited and updated information about each section of the docker and the usage.
+ Added info about the new visualization of frames/blanks/holds.
+ Added info about the new insert multiple frames/columns feature.
+ Added some info about audio.
+ Fixed a bug which had swapped the labels for the menu and zoom/resizer handle.
~ Split the middle section under a "usage" header.
~ Pushed the GUI Actions content to the bottom to keep all of the text body together.
~ I changed the order of some of the elements in the legend, as the updated image is labeled in a slightly different order.
I haven't configured sphinx yet, so I wasn't haven't actually built these changes. I assume they're fine, as a played it pretty close to what was already there. But it's possible that I added whitespace and things that may affect the formatting in an undesirable way. Let me know if there is anything I need to change, add, or even remove! =]