[doc] Bring back examples to page shortcut methods
[doc] Bring back examples to page shortcut methods

The motivation behind the patch:
- examples are probably the most valuable thing in the doc
- currently, one would need to navigate to `page.evaluate` and then
  click to the `frame.evaluate` to see the example.
- with this patch, all the descriptions for the shortcut methods are
  copied as well. So there's an example for `page.evaluate` right
  away.

Drive-by: fix links for `page.$` and `page.$$`

brutalcrozt/puppeteer,GoogleChrome/puppeteer,brutalcrozt/puppeteer,puppeteer/puppeteer,ianchn/puppeteer,GoogleChrome/puppeteer,ianchn/puppeteer,puppeteer/puppeteer,puppeteer/puppeteer,puppeteer/puppeteer,a1ph/puppeteer,michaelfward/puppeteer,GoogleChrome/puppeteer,elisherer/puppeteer,a1ph/puppeteer,elisherer/puppeteer,michaelfward/puppeteer