add site specific docs, replace Metacentrum cloud with e-INFRA CZ cloud

topics/compute/concepts/docs/index.md

...mpute/openstack/docs/additional-information/contribute.md

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

topics/compute/openstack/docs/additional-information/faq.md

...stack/docs/additional-information/ip-allocation-policy.md

...compute/openstack/docs/additional-information/register.md

...openstack/docs/additional-information/terms-of-service.md

...enstack/docs/additional-information/virtual-networking.md

...mpute/openstack/docs/how-to-guides/accessing-instances.md

topics/compute/openstack/docs/index.md

...mpute/openstack/docs/technical-reference/brno-site/faq.md

...e/openstack/docs/technical-reference/brno-site/flavors.md

...penstack/docs/technical-reference/brno-site/get-access.md

...enstack/docs/technical-reference/brno-site/get-support.md

...stack/docs/technical-reference/brno-site/gpu-computing.md

...ute/openstack/docs/technical-reference/brno-site/index.md

...penstack/docs/technical-reference/brno-site/networking.md

...k/docs/technical-reference/brno-site/openstack-modules.md

...nstack/docs/technical-reference/brno-site/quota-limits.md

...te/openstack/docs/technical-reference/ostrava-site/faq.md