vagrant: Fix missing doc. dependency error
vagrant: Fix missing doc. dependency error

The dev. VM provisioning currently fails with the following error
because of a missing documentation dependency:

      runtime1: make[1]: Leaving directory '/home/vagrant/go/src/github.com/cilium/cilium/Documentation'
      runtime1: contrib/scripts/lock-check.sh
      runtime1: make[1]: Entering directory '/home/vagrant/go/src/github.com/cilium/cilium'
      runtime1: (make -C Documentation/ dummy SPHINXOPTS="" 2>&1 && touch check-docs.ok) \
      runtime1: 	| grep -v "tabs assets"
      runtime1: make[2]: Entering directory '/home/vagrant/go/src/github.com/cilium/cilium/Documentation'
      runtime1: Documentation dependency 'pyenchant' not found.
      runtime1: Run 'pip3 install --user -r Documentation/requirements.txt'
      runtime1: Makefile:27: recipe for target 'check-requirements' failed
      runtime1: make[2]: *** [check-requirements] Error 2
      runtime1: make[2]: Leaving directory '/home/vagrant/go/src/github.com/cilium/cilium/Documentation'
      runtime1: Makefile:451: recipe for target 'check-docs' failed
      runtime1: make[1]: Leaving directory '/home/vagrant/go/src/github.com/cilium/cilium'
      runtime1: Makefile:456: recipe for target 'postcheck' failed
      runtime1: make[1]: *** [check-docs] Error 2
      runtime1: make: *** [postcheck] Error 2
  The SSH command responded with a non-zero exit status. Vagrant
  assumes that this means the command failed. The output for this command
  should be in the log above. Please read the output to determine what
  went wrong.

There's already a pull request open to add the missing dependency to the
upstream VM image, but we need to add it to the Vagrant provisioning as
well to fix the error until we build a new image.

Reported-by: Michal Rostecki <82ebf970c69340aebb770c3853be5fd96a3eb584@suse.com>
Signed-off-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

cilium/cilium,tklauser/cilium,tklauser/cilium,cilium-team/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium-team/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium