docs: correct closing tags for option elements in HTML examples

[sangcnguyen]

I noticed some incorrect usage of enclosing tags. This PR corrects those issues.

[github-actions]

Test results for "tests 1"

11 flaky

⚠️ [firefox-page] › tests/page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [installation tests] › tests/playwright-electron-should-work.spec.ts:44:5 › should work when wrapped inside @playwright/test and trace is enabled @package-installations-macos-latest
⚠️ [chromium-library] › tests/library/headful.spec.ts:233:3 › should click in OOPIF @ubuntu-20.04-chromium-tip-of-tree
⚠️ [playwright-test] › tests/ui-mode-test-ct.spec.ts:117:5 › should run component tests after editing test and component @ubuntu-latest-node20-1
⚠️ [webkit-library] › tests/library/browsercontext-clearcookies.spec.ts:52:3 › should remove cookies by name @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/browsercontext-clearcookies.spec.ts:72:3 › should remove cookies by name regex @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/browsertype-connect.spec.ts:199:5 › launchServer › should be able to connect two browsers at the same time @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/trace-viewer.spec.ts:773:1 › should handle src=blob @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-filechooser.spec.ts:24:5 › should upload multiple large files @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-screenshot.spec.ts:565:7 › page screenshot › mask option › should hide elements based on attr @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-set-input-files.spec.ts:204:5 › should upload large file with relative path @webkit-ubuntu-22.04-node18

38642 passed, 794 skipped
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Merge workflow run.

[mxschmitt]

Thanks.