add contributor for #8978
add contributor for #8978

rsalmaso/wagtail,zerolab/wagtail,wagtail/wagtail,thenewguy/wagtail,wagtail/wagtail,zerolab/wagtail,zerolab/wagtail,rsalmaso/wagtail,thenewguy/wagtail,rsalmaso/wagtail,wagtail/wagtail,rsalmaso/wagtail,thenewguy/wagtail,rsalmaso/wagtail,wagtail/wagtail,zerolab/wagtail,zerolab/wagtail,thenewguy/wagtail,wagtail/wagtail,thenewguy/wagtail