viz.plot_alignment()'s "R" key binding doesn't fully reset the scene

Bug:
I was told that pressing the R key in the figure created by plot_alignment() is supposed to reset the camera / head to its initial position. However, it appears to only move the camera to a pre-defined distance from the center (which is not equal to the initial distance when the figure is first created), but doesn't reset any rotation, which is what I'm usually most concerned about.

Feature request:
Also I didn't know there even were keyboard shortcuts until @agramfort told me so. Would be nice to make this more discoverable – thinking of something like the toolbar we have for Brain, but simply adding some text, e.g., "Press R to reset the view" would already be very helpful.

cc @GuillaumeFavelier

Start by locating the implementation and keyboard handler for viz.plot_alignment(), then reproduce the R-key behavior and compare it with the scene's initial camera and rotation. Done means R restores the initial view, including rotation, and the figure makes the shortcut discoverable through text or a toolbar-like cue.