That’s the opposite of what Venus needs. It needs less heat, rather than more. JHS:Terra* calls it a “sunshade”, and confirms that it was stationed at the L1.
*To the OP: I know you said you don’t have a lot of books, but I do want to mention JHS:Terra. It’s got a long article on the history of Venus and it’s terraforming. If you get one book for Venus data, get that one.