Gorm Document batch delete by providing slice of structs

Describe the feature

When doing a db.Delete and passing a slice of structs, GORM will do a batch delete of all elements in the slice. This is not clearly documented. Let's add this to the documentation for clarity.

See: https://stackoverflow.com/q/75362946/5343140

Motivation

The documentation is not clear on this.

Related Issues

Comment From: a631807682

Welcome to create a PR for it. https://github.com/go-gorm/gorm.io

Comment From: dogenkigen

Seems like the documentation is clear about it now: https://gorm.io/docs/delete.html#Batch-Delete