Add a page on sleep and wait for browser module

[ankur22]

What?

This new page details recommendation on sleep and the various wait* functions available to the browser module. The main reason for doing this is to guide users away from working with sleep and instead work with the various wait* APIs, specifically replacing sleep with page.waitForTimeout.

Checklist

• I have used a meaningful title for the PR.
• I have described the changes I've made in the "What?" section above.
• I have performed a self-review of my changes.
• I have run the npm start command locally and verified that the changes look good.

• I have made my changes in the docs/sources/next folder of the documentation.

Related PR(s)/Issue(s)