Update credentials.md

docs/docs/providers/credentials.md

@@ -44,6 +44,7 @@ providers: [
   CredentialsProvider({
     // The name to display on the sign in form (e.g. "Sign in with...")
     name: "Credentials",
+    id:"credentials",
     // `credentials` is used to generate a form on the sign in page.
     // You can specify which fields should be submitted, by adding keys to the `credentials` object.
     // e.g. domain, username, password, 2FA token, etc.