Remove the PACKAGECONFIG for documentation as it now requires python3-sphinx which is not
provided in any existing recipe.
(From OE-Core rev: 32dded1bd2f6c5cf6437330830399b72f15096c4)
Signed-off-by: Derek Straka <derek@asterius.io>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
