fix documentation markdown conversion issue
fix documentation markdown conversion issue

- introduced in #8569

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