The ornamental design for a documentshredder, as shown and described.
FIG. 1 is a perspective front view of the document shredder according to my new design;
FIG. 2 is a perspective rear view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The wire frame lines shown throughout the views indicate surface contour.
The broken lines immediately adjacent to the claim depict the bounds of the claimed design, while all other broken lines are directed to environment. The broken lines form no part of the claimed design.