Clarified information about the default file size limits for Googlebot

What : While moving over the information about the default file size limits of Google’s crawlers and fetchers to the crawler documentation , we also updated the Googlebot documentation about its own file size limits. Why : The original location of the default file size limits was not the most logical place as it applies to all of Google’s crawlers and fetchers, and the move enabled us to be more precise about Googlebot’s limits.