Add UOS 20 removal to docs

[Mab879]

Description:

Add UOS 20 removal to docs

Rationale:

Follow the process.
Even though 0.1.74 has not been released yet it will be the last one with the product.

[github-actions]

Start a new ephemeral environment with changes proposed in this pull request:

Fedora Environment

Oracle Linux 8 Environment

[github-actions]

🤖 A k8s content image for this PR is available at:
ghcr.io/complianceascode/k8scontent:12257
This image was built from commit: 0226459

Click here to see how to deploy it

If you alread have Compliance Operator deployed:
utils/build_ds_container.py -i ghcr.io/complianceascode/k8scontent:12257

Otherwise deploy the content and operator together by checking out ComplianceAsCode/compliance-operator and:
CONTENT_IMAGE=ghcr.io/complianceascode/k8scontent:12257 make deploy-local

[codeclimate]

Code Climate has analyzed commit 0226459 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 59.4% (0.0% change).

View more on Code Climate.