profile-manual: usage.rst: further style improvements
According to errors reported by "make stylecheck"
(From yocto-docs rev: fc808b2dca4321209bfa6206d9e43aa1a5a0c5b8)
Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>