Add PoC section and remove unnecessary content

[dsatlawa]

Description

Created a draft of a full PoC section under Solutions -> Enterprise Cloud Bleprints -> PoC
Removed old image files and PoC section for OpenNebula CE edition

Branches to which this PR applies

• master
• one-X.X

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• Check this if this PR should not be squashed

[tinova]

@dsatlawa doesn't render

WARN  deprecated: .Language.LanguageDirection was deprecated in Hugo v0.158.0 and will be removed in a future release. Use .Language.Direction instead.
WARN  deprecated: .Site.LanguageCode was deprecated in Hugo v0.158.0 and will be removed in a future release. Use .Site.Language.Locale instead.
ERROR [en] REF_NOT_FOUND: Ref "deploy_opennebula_onprem_with_poc_iso": "/Users/cvazquez/dev/one-docs/content/getting_started/install_opennebula/evaluation/validate_the_environment.md:19:187": page not found
WARN  deprecated: .Site.AllPages was deprecated in Hugo v0.156.0 and will be removed in a future release. See https://discourse.gohugo.io/t/56732.
Built in 3567 ms
ERROR error building site: logged 1 error(s)

[tinova]

I see the PoC section in Enterprise Cloud Blueprints, but it should be in its original place (as in master), under Engieering Blueprints

[tinova]

please rebase and check with master and one-7.4, the guides have other names https://docs.opennebula.io/7.4/