Add banner for security update

[mikemckiernan]

Review HTML:

• toolkit: https://nvidia.github.io/cloud-native-docs/review/pr-110/container-toolkit/latest/index.html
• gpu-op: https://nvidia.github.io/cloud-native-docs/review/pr-110/gpu-operator/latest/index.html
• ocp: https://nvidia.github.io/cloud-native-docs/review/pr-110/openshift/latest/index.html

My only uncertainty is how this banner might interact with a "version selector" warning when someone selects an older version of the docs.

@francisguillier, @cdesiniotis, @elezar, PTAL.

[github-actions]

Documentation preview

https://nvidia.github.io/cloud-native-docs/review/pr-110

[francisguillier]

@mikemckiernan
can we add the reference to this link in the message?
https://nvidia.custhelp.com/app/answers/detail/a_id/5582

[mikemckiernan]

@mikemckiernan can we add the reference to this link in the message? https://nvidia.custhelp.com/app/answers/detail/a_id/5582

Updated. I used the bulletin heading as the link text. PLMK any more suggs. TY!

[francisguillier]

all good for me.
thanks Mike!