Merge branch 'feature/upd-openstack' into 'master'

...te/openstack/docs/additional-information/custom-images.md

...ack/docs/getting-started/creating-first-infrastructure.md

...e/openstack/docs/how-to-guides/allocating-floating-ips.md

...mpute/openstack/docs/how-to-guides/attaching-interface.md

...ute/openstack/docs/how-to-guides/changing-vm-resources.md

...compute/openstack/docs/how-to-guides/create-networking.md

docs/compute/openstack/docs/how-to-guides/manage-volumes.md

.../openstack/docs/how-to-guides/managing-security-groups.md

...compute/openstack/docs/how-to-guides/obtaining-api-key.md

docs/compute/openstack/docs/images/EGI.png

docs/compute/openstack/docs/images/EOSC_logo.png

docs/compute/openstack/docs/images/app_creds_1.png

docs/compute/openstack/docs/images/app_creds_2.png

docs/compute/openstack/docs/images/c4ew.png

docs/compute/openstack/docs/images/elixir_czechrepublic.png

docs/compute/openstack/docs/images/ics-logo.png

docs/compute/openstack/docs/images/illustration.png

docs/compute/openstack/docs/images/image_visibility.png

docs/compute/openstack/docs/images/instance/instance1.png

docs/compute/openstack/docs/images/instance/instance2.png