chore: add docs for experimental 'watch mode'

[mxschmitt]

No description provided.

[github-actions]

Test results for "tests 1"

6 flaky

⚠️ [chromium-library] › library/video.spec.ts:381:5 › screencast › should capture navigation @ubuntu-20.04-chromium-tip-of-tree
⚠️ [playwright-test] › ui-mode-test-update.spec.ts:83:5 › should pick new / deleted tests @ubuntu-latest-node20-1
⚠️ [webkit-library] › library/debug-controller.spec.ts:142:1 › should reset for reuse @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/selector-generator.spec.ts:40:5 › selector generator › should prefer role=button over inner span @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › library/signals.spec.ts:78:7 › signals › should close the browser on SIGINT @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › page/page-set-input-files.spec.ts:205:3 › should upload multiple large files @webkit-ubuntu-22.04-node18

37269 passed, 650 skipped
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Merge workflow run.