The ornamental design for a detergenttablet, as shown and described.
FIG. 1 is a perspective view of a detergent tablet showing the new design;
FIG. 2 is an end view thereof both ends appearing the same;
FIG. 3 is a side view thereof both sides appearing the same; and,
FIG. 4 is a top plan view.
The stippling in the drawings is representative of color contrast, not
pattern. The surface(s) or portion(s) of the article not shown in the
drawing or described in the specification form(s) no part of the claimed
design.