Bug 27108: Add 21.05 release team to teams.yaml

Bug 27108: Add 21.05 release team to teams.yaml

This patch update the docs/teams.yaml file to add the elected 21.05
release team and update the include to reflect the minor change of
structure.

Test plan.
1/ Apply the patch
2/ Update Koha.pm to state 20.11.00.000
3/ Update preferences to Version to 20.1100000
4/ Navigate to the about page
5/ Note that the 20.11 team is shown on the left and the new 21.05 team
is shown on the right.
6/ Pay particular attention to the 'Packaging manager' on the left and
'Packaging team' on the right. (We have not had a team of packaging
people before, so the template had to be updated to allow for an array
of packaging people).
7/ Signoff.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Bug 27108: (QA follow-up) Fix Agustin and Documentation manager

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>