Update linkedin-page.mdx

reverts change to env-vars

Author: joelclaudio

pages/providers/linkedin-page.mdx

@@ -26,7 +26,7 @@ It is important to request the Advertising API permissions and fill up the reque
 Copy the created `Client ID` and `Client Secret` and add them to your `.env` file.
 
 ```env
-SERVICE_LINKEDIN_ID=""
-SERVICE_LINKEDIN_SECRET=""
+LINKEDIN_CLIENT_ID=""
+LINKEDIN_CLIENT_SECRET=""
 ```
 You can find those under the Auth Tab of your LinkedIn App in the developer portal.