docs(zod-validator) - Update README.md to include an example with a custom validator wrapper for improved type inference (#922)

* docs: add custom validator example for improved type inference

* Update README.md - removed default value of target

packages/zod-validator/README.md

@@ -47,12 +47,18 @@ import { ZodSchema } from "zod";
 import type { ValidationTargets } from "hono";
 import { zValidator as zv } from "@hono/zod-validator";
 
-export const zValidator = (target: keyof ValidationTargets,  schema: ZodSchema) => 
+export const zValidator = <
+  T extends ZodSchema,
+  Target extends keyof ValidationTargets
+>(
+  target: Target,
+  schema: T
+) =>
   zv(target, schema, (result, c) => {
     if (!result.success) {
       throw new HTTPException(400, { cause: result.error });
     }
-})
+  });
 
 // usage
 import { zValidator } from './validator-wrapper'