colors.cmyk: adding some docs.

extra/colors/cmyk/cmyk-docs.factor

@@ -0,0 +1,15 @@
+
+IN: colors.cmyx
+
+HELP: cmyka
+{ $class-description "The class of CMYK (Cyan, Magenta, Yellow, Black) colors with an alpha channel. All slots store values in the interval " { $snippet "[0,1]" } "." } ;
+
+ARTICLE: "colors.cmyk" "CMYK colors"
+"THe " { $vocab-link "colors.cmyk" } " vocabulary implements colors specified by their cyan, magenta, yellow, and black components, together with an alpha channel."
+{ $subsections
+    cmyka
+    <cmyka>
+    cmyka>gray
+    rgba>cmyka
+}
+{ $see-also "colors" } ;