add(examples/styles): text and color styling possiblities

This also contains some minor refactoring to improve the readability
and understandability of the library (i.e. renaming of Style.Attributes
to Style.Emphasis).

src/style.zig

@@ -22,7 +22,7 @@ pub const Underline = enum {
     dashed,
 };
 
-pub const Attribute = enum(u8) {
+pub const Emphasis = enum(u8) {
     reset = 0,
     bold = 1,
     dim,
@@ -38,7 +38,7 @@ fg: Color = .white,
 bg: Color = .default,
 ul: Color = .default,
 ul_style: Underline = .off,
-attributes: []const Attribute,
+emphasis: []const Emphasis,
 
 pub fn eql(this: Style, other: Style) bool {
     return std.meta.eql(this, other);
@@ -60,9 +60,7 @@ pub fn value(this: Style, writer: anytype, cp: u21) !void {
     try std.fmt.format(writer, ";", .{});
     try this.ul.write(writer, .ul);
     // append styles (aka attributes like bold, italic, strikethrough, etc.)
-    for (this.attributes) |attribute| {
-        try std.fmt.format(writer, ";{d}", .{@intFromEnum(attribute)});
-    }
+    for (this.emphasis) |attribute| try std.fmt.format(writer, ";{d}", .{@intFromEnum(attribute)});
     try std.fmt.format(writer, "m", .{});
     // content
     try std.fmt.format(writer, "{s}", .{buffer});