graphics/pngcrush: Wrap README at 72 columns.

Signed-off-by: B. Watson <yalhcru@gmail.com>

graphics/pngcrush/README

@@ -1,6 +1,6 @@
 Pngcrush is an optimizer for PNG (Portable Network Graphics) files.
 It can be run from a commandline in an MSDOS window, or from a UNIX or
-LINUX commandline.  Its main purpose is to reduce the size of the PNG IDAT
-datastream by trying various compression levels and PNG filter methods.
-It also can be used to remove unwanted ancillary chunks, or to add
-certain chunks including gAMA, tRNS, iCCP, and textual chunks.
+LINUX commandline. Its main purpose is to reduce the size of the PNG
+IDAT datastream by trying various compression levels and PNG filter
+methods. It also can be used to remove unwanted ancillary chunks, or
+to add certain chunks including gAMA, tRNS, iCCP, and textual chunks.