RHOAIENG-9707: chore(tests/containers): update README.md with testcontainers motivation and lima section

[jiridanek]

Description

• https://issues.redhat.com/browse/RHOAIENG-9707

this is the readme updates from

• [WIP] RHOAIENG-9707 ci: dynamic testing of container images with pytest #629

How Has This Been Tested?

• https://github.com/jiridanek/notebooks/actions/runs/13026937955

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[jstourac]

/lgtm

[jiridanek]

/override ci/prow/images
/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jiridanek

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[openshift-ci]

@jiridanek: Overrode contexts on behalf of jiridanek: ci/prow/images

In response to this:

/override ci/prow/images
/approve

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