The ornamental design for a notebook, as shown and described.
FIG. 1 is a front perspective view of the notebook;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a rear view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a rear perspective view thereof; and,
FIG. 9 is a second front perspective view thereof showing the notebook binding structure in an unbound state in order to show the cover in a lifted state.
The broken lines immediately adjacent to the shaded areas represent the bounds of the claimed design while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design.