I received an email from Google saying my site has some mobile usabilityissues. The email said the following:Weve found critical mobile usability issues in pages on my website.  Mobile usability errors can severely affect the user experience of  your site. Pages with mobile usability issues may be ranked lower in  Google search results on mobile devices.We recommend following Googles Mobile Usability guidelines to avoid  negatively affecting your site ranking on Google Search.I did some mobile-friendly tests on my site with Google webmaster mobile-friendly tool:When I did these tests for different pages I got variations of thismessage: This page uses 23 resources which are blocked by robots.txt.Most of the resources it lists as blocked are in /wp-content or/wp-contains.I want to know how I can fix these issues in my robots.txt. 
Google mobile usability errors
google search;mobile;usability;googlebot mobile