Update hooks.rst (#5044)
Update hooks.rst (#5044)

Document and Image fields changed from `uploaded_by` to `uploaded_by_user`

kaedroho/wagtail,timorieber/wagtail,wagtail/wagtail,FlipperPA/wagtail,jnns/wagtail,mixxorz/wagtail,mikedingjan/wagtail,rsalmaso/wagtail,wagtail/wagtail,torchbox/wagtail,nealtodd/wagtail,nimasmi/wagtail,thenewguy/wagtail,gasman/wagtail,nealtodd/wagtail,zerolab/wagtail,torchbox/wagtail,kaedroho/wagtail,thenewguy/wagtail,gasman/wagtail,zerolab/wagtail,thenewguy/wagtail,nimasmi/wagtail,wagtail/wagtail,thenewguy/wagtail,wagtail/wagtail,rsalmaso/wagtail,torchbox/wagtail,zerolab/wagtail,kaedroho/wagtail,nealtodd/wagtail,nimasmi/wagtail,jnns/wagtail,mixxorz/wagtail,zerolab/wagtail,kaedroho/wagtail,kaedroho/wagtail,mixxorz/wagtail,gasman/wagtail,wagtail/wagtail,gasman/wagtail,FlipperPA/wagtail,FlipperPA/wagtail,nimasmi/wagtail,takeflight/wagtail,thenewguy/wagtail,rsalmaso/wagtail,mikedingjan/wagtail,FlipperPA/wagtail,torchbox/wagtail,jnns/wagtail,timorieber/wagtail,mixxorz/wagtail,rsalmaso/wagtail,nealtodd/wagtail,rsalmaso/wagtail,takeflight/wagtail,mikedingjan/wagtail,timorieber/wagtail,takeflight/wagtail,jnns/wagtail,takeflight/wagtail,mikedingjan/wagtail,zerolab/wagtail,gasman/wagtail,timorieber/wagtail,mixxorz/wagtail