Update README.md

Author: razor-x

README.md

@@ -24,7 +24,7 @@ However, some additional input cases are handled:
 - For `z.boolean()`, the following strings are parsed as `true`:
   `true`, `True`, `TRUE`, `yes`, `Yes`, `YES`, and `1`.
 - For `z.boolean()`, the following values are parsed as `false`:
-  `false`, `False`, `FALSE`, `no`, `No`, `NO`, and '0'.
+  `false`, `False`, `FALSE`, `no`, `No`, `NO`, and `0`.
 - Parses `z.array()` in the following formats.
   In order to support unambiguous parsing, array string values
   containing a `,` are not supported.