[FEATURE] Bring in original source URL for articles coming in from Readwise Reader

**Is your feature request related to a problem? Please describe.**

Not a problem, just a desired enhancement.

**Describe the solution you'd like**

Just like you have properties (slots) for Category, Image and Author... it would be super valuable if you had one for "Source" or "URL" or "Location" or whatever name you want to use which for web articles coming in from Readwise Reader it would be the source URL to the original location of the article. Not only would this be valuable to have in RemNote as a datapoint, but it would then allow for auto linking to anywhere else within your RemNote KB that you may have saved/pasted that article URL in your other notes. This would be extremely useful for me!