slightly update wording

Author: Le0Developer

src/content/docs/turnstile/get-started/server-side-validation.mdx

@@ -290,7 +290,7 @@ A validation error is indicated by having the `success` property set to `false`.
 | <div style="width:200px">Error code</div> | Description                                                                                                                                                                 |
 | ----------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `missing-input-secret`                    | The secret parameter was not passed.                                                                                                                                        |
-| `invalid-input-secret`                    | The secret parameter was invalid, did not exist, or used a [testing secret key](/turnstile/troubleshooting/testing) with a non-testing response.                            |
+| `invalid-input-secret`                    | The secret parameter was invalid, did not exist, or is a [testing secret key](/turnstile/troubleshooting/testing) with a non-testing response.                              |
 | `missing-input-response`                  | The response parameter (token) was not passed.                                                                                                                              |
 | `invalid-input-response`                  | The response parameter (token) is invalid or has expired. Most of the time, this means a fake token has been used. If the error persists, contact customer support.         |
 | `bad-request`                             | The request was rejected because it was malformed.                                                                                                                          |