remove obsolete TypeScript standalone example pre Cypress 4.4.0 (#5265)

Author: MikeMcC399

docs/guides/tooling/typescript-support.mdx

@@ -214,8 +214,6 @@ As you can see there are generic parameters `<'type', 'element'>` are used:
 
 #### Examples:
 
-- Find
-  [the standalone example](https://github.com/cypress-io/add-cypress-custom-command-in-typescript).
 - See
   [Adding Custom Commands](https://github.com/cypress-io/cypress-example-recipes#fundamentals)
   example recipe.