docs.rst is the landing page for the documentation from the libcamera
website, but isn't particularly introductory. Move much of the content
from guides/introduction.rst to docs.rst, which will serve as the new
introductory page. Remove guides/introduction.rst.
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
