added more detail to the split views page of the docs

[churuzzz]

New Screenshot

New screenshot to show what the context menu option for "Split X Tabs" looks like in the side bar.

Second commit changed the screenshot to something that's a bit more pleasing to look at than just a window screenshot

New subsections for "Create a Split View"

• Added drag description as well as a link to how to disable it.
• Added context menu option through multi-select.
• Added shortcut usage description.
• Added reference to the new "Create Empty Split View" feature.

Edits to the Shortcuts at the bottom

• Added the new shortcut, specifying the difference between the Linux bind. May need to be edited because I couldn't find a reference to what the default was for Mac
• Added a callout that the shortcuts only work for creating a new split view and won't disable the split view or change it by reusing the shortcuts.
• Changed section name to reflect the newly added shortcut not being labeled as a "Toggle" in the browser preferences.

Resolves #231