doc(showcase): add a readme to explain how to update the screenshots for visual testing

[fpaul-1A]

Proposed change

Related issues

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[nx-cloud]

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✅ Successfully ran 11 targets

• nx run-many --target=test-int --parallel 3
• nx run-many --target=test-e2e --parallel 3
• nx run-many --target=build --projects=eslint-plugin --parallel 3
• nx run-many --target=publish --parallel 3 --nx-bail --userconfig .verdaccio/conf/.npmrc-logged --tag=latest --@o3r:registry=http://127.0.0.1:4873 --@ama-sdk:registry=http://127.0.0.1:4873 --@ama-terasu:registry=http://127.0.0.1:4873 --@o3r-training:registry=http://127.0.0.1:4873
• nx run-many --target=documentation --parallel 3
• nx affected --target=test --parallel 3 --cacheDirectory=D:\a\otter\otter/.cache/jest --base=remotes/origin/main --collectCoverage
• nx run ama-sdk-schematics:build-swagger
• nx run-many --target=build --parallel 3
• nx affected --target=test --parallel 3 --cacheDirectory=/home/runner/work/otter/otter/.cache/jest --base=remotes/origin/main --collectCoverage
• nx run-many --target=build-swagger --parallel 3
• nx affected --target=lint --parallel 3 --base=remotes/origin/main --configuration ci

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.08%. Comparing base (331f0da) to head (9dee21d).
Report is 8 commits behind head on main.

✅ All tests successful. No failed tests found.

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[vscaiceanu-1a]

No need to add the pattern here. As you can see, all urls that start with http are ignored already.