doc: rockchip: restyle rockchip.rst

With more text coming to the rockchip.rst document,
give it a restyle first.

Changed:
  sort build examples alphabetically
  add git clone example
  fix bash examples
  fix phrases (grammer)
  fix typos

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
1 file changed