Allow the manual changing of the HTML that will be added in Add more contents URLs for content behind signup flow

[baditaflorin]

I want my agent to know what is written in the settings page, what is written on integrations page etc that are behind a signup page, so now when I add the pages it will scrape and get just the sign in redirects.
It would be useful to allow us to manually input the html or override it so we can have the knowledge library know about the real content.