docs: Update credentials.mdx (#11182)

Author: amanhuh

docs/pages/getting-started/authentication/credentials.mdx

@@ -226,7 +226,7 @@ export function SignIn() {
 
 ## Verifying Data with Zod
 
-To improved the security of your `Credentials` provider use, we can leverage a run-time schema validation library like [Zod](https://zod.dev) to validate that the inputs match what we expect.
+To improve the security of your `Credentials` provider use, we can leverage a run-time schema validation library like [Zod](https://zod.dev) to validate that the inputs match what we expect.
 
 ```bash npm2yarn
 npm install zod