The ornamental design for a rail, as shown and described.
FIG. 1 is an isometric perspective view of a rail in accordance with our design;
FIG. 2 is a right side elevation view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a top plan view thereof.
The rail is shown with a symbolic break in its length. The appearance of any portion of the rail between the break lines forms no part of the claimed design.