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 a side view thereof as seen from all sides; and,
FIG. 3 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.