Update containers.rst

[ilyakimavets]

Add set up config in creating container. And fix mistake in container save method

[ajkavanagh]

Hi @ilyakimavets, thanks for the PR. However, due to the new policy github lxc organisation, all commits need a 'signed off' line. (see the DCO fail above).

The easiest way to do this is (in your git branch with your recent commit):

git commit -s --amend --no-edit
git push <your remote> -f

The '-f' just force updates the commit and the PR will be updated. The DCO check above will then be satisfied.

Thanks very much, and sorry for the small annoyance on commits here.

[ajkavanagh]

Hi @ilyakimavets, please could you rebase your PR as it's now got conflicts with the base. Thanks very much!

[ajkavanagh]

Needs rebasing please.

[ajkavanagh]

I've rebased this and merged it via #385.