change documentation link

Co-authored-by: Jennifer Shehane <[email protected]>

packages/driver/src/cypress/error_messages.ts

@@ -805,7 +805,7 @@ export default {
     },
     invalid_new_command: {
       message: '`Cypress.Commands.add()` is used to create new commands, but `{{name}}` is an existing Cypress command.\n\nPlease use `Cypress.Commands.overwrite()` if you would like to overwrite an existing command.\n',
-      docsUrl: 'https://docs.cypress.io/api/cypress-api/custom-commands',
+      docsUrl: 'https://on.cypress.io/custom-commands',
     },
     invalid_overwrite: {
       message: 'Cannot overwite command for: `{{name}}`. An existing command does not exist by that name.',