[Feature] Document that non-fixture contexts/pages should be closed when no longer needed

When a BrowserContext is not obtained from a Playwright Test fixture, but from browser.newContext() in a test or when using Playwright Library, it should be closed once no longer needed (according to @mxschmitt at https://stackoverflow.com/questions/72284057/do-playwright-browser-contexts-opened-manually-need-to-be-closed?noredirect=1#comment127709001_72284057). Similarly pages from context/browser.newPage() should be closed if they are no longer needed and the context is long-living.

However, I wasn’t able to find any place in documentation and examples saying this; the only hint was the existence of close methods. Please consider documenting it.

[alikirec]

It’s already mentioned in https://playwright.dev/docs/api/class-browsercontext – at the end of the first code snippet

// Dispose context once it's no longer needed.
await context.close();

[rwoll]

Closing as part of triage per above.