docs: Update handleSubmit error handling example with setError usage

Author: den025

src/content/docs/useform/handlesubmit.mdx

@@ -38,6 +38,10 @@ This function will receive the form data if form validation is successful.
       // await fetch()
     } catch (e) {
       // handle your error
+      setError("service", {
+        type: "custom",
+        message: "something went wrong",
+      })
     }
   }
 

src/data/api.tsx

@@ -967,6 +967,10 @@ handleSubmit(async (data) => await fetchAPI(data))`}
     // await fetch()
   } catch (e) {
     // handle your error
+    setError("service", {
+      type: "custom",
+      message: "something went wrong",
+    })
   }
 };