Add privacy warning

[Rudxain]

If a repo script persistently stores sensitive data (as cookie, localStorage, etc...), then other repos opened by the user will also have access to this data. This isn't inherently a problem of bypassing CORS, so it should be mentioned as an additional risk (both in the README and the index)

I haven't tested if this "vulnerability" actually works, but I assume it's likely that it can be easily exploited

[hoijui]

Sorry, I did not get notifications for this repo, even though I created it. :/
(now I do)
... and you can now do this yourself! :-)

[Rudxain]

Thank you for the invite! I'm sorry for being late: I was sleeping, and I had to do some stuff.

I've created a separate branch, and I'll merge to master when ready.

For some reason, I can't link the branch to this issue, so I'll open a PR