Fixed unicode literal

exercises/059_integers.zig

@@ -7,7 +7,7 @@
 //     const a3: u8 = 0o101;       // octal
 //     const a4: u8 = 0b1000001;   // binary
 //     const a5: u8 = 'A';         // ASCII code point literal
-//     const a6: u16 = 'Ȁ';      // Unicode code points can take up to 21 bits
+//     const a6: u16 = '\u{0041}'; // Unicode code points can take up to 21 bits
 //
 // You can also place underscores in numbers to aid readability:
 //