update latest.txt for 2.16.2 and 2.15.5
update latest.txt for 2.16.2 and 2.15.5

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