The ornamental design for surface indicia for a package, as shown and described.
FIG. 1 is a perspective view of surface indicia for a package;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a front elevational view thereof;
FIGS. 4 and 5 are side elevational views thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines are for illustrative purpose only and form no part of the claimed design. The grey scale is not limited to the different shades of grey, but is intended to indicate that the design is not limited to a specific color combination.