Extra info/tips for options pages

[AntonOfTheWoods]

The default vite index.html uses <script type="module" src="index.tsx"></script> for getting the script to run but this seems to be ignored, or at least silently fail for an options page. <script type="module" src="./index.tsx"></script> seems to work as expected. This took a while to find and might be good to put somewhere in the docs if it is the expected behaviour. I can submit a change if that is appropriate!