4.0 release notes - fix layout of UX Unification section
4.0 release notes - fix layout of UX Unification section

- also fix typo in instructions

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