docs: ref-manual: ref-system-requirements: update requirements to build Sphinx docs

Tested with containers on all supported distributions.

Debian 8 (Jessie) still has Python3.4 and an old pip3, which makes it
impossible to build typing module which is a requirement of "new" Sphinx
python module.

One cannot update to latest pip3 from within pip in Jessie's version.
One cannot get a newer pip from upstream because newer pip don't support
Python3.4 anymore.
One cannot build with python3-sphinx package from Jessie because the
package is too old (1.2.3) and does not have sphinx.ext.autosectionlabel
module which appeared in 1.4 version.

(From yocto-docs rev: 14da565986a573ac7e0b5c5943e55b7b74f99dd5)

Signed-off-by: Quentin Schulz <foss@0leil.net>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/documentation/poky.yaml b/documentation/poky.yaml
index 14f45055d7..d50b8321a3 100644
--- a/documentation/poky.yaml
+++ b/documentation/poky.yaml
@@ -86,3 +86,4 @@ CENTOS8_HOST_PACKAGES_ESSENTIAL : "-y epel-release
      socat perl-Data-Dumper perl-Text-ParseWords perl-Thread-Queue python3-pip \
      python3-GitPython python3-jinja2 python3-pexpect xz which SDL-devel xterm \
      rpcgen mesa-libGL-devel"
+PIP3_HOST_PACKAGES_DOC : "$ sudo pip3 install sphinx sphinx_rtd_theme pyyaml"