doc: re-format maintainer.rst file rendering
doc: re-format maintainer.rst file rendering

Signed-off-by: Manish Pandey <f72a68396f72e54a6338d46190da5e42d7475246@arm.com>
Change-Id: I9fafeb966eeec35527647282b953d88f6aa383be

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware