Add prominent links to the API docs in README
Add prominent links to the API docs in README

Section headings in the README now link to the API documentation on godoc.org
mesosphere/testify,outrightmental/go-testify,irnnr/testify,ANPez/testify,MCProHosting/testify,ernesto-jimenez/testify,AnuchitPrasertsang/testify,yxd-hde/testify,glittershark/testify,Fiery/testify,allgeek/testify,stretchr/testify,multiplay/testify,grepory/testify,hpcloud/testify,yaoshipu/testify,ifraixedes/testify,pki-io/testify,hawx/assert,davelondon/ktest,csquared/testify,liudhzhyym/testify,danielchatfield/testify,insionng/testify,bmatsuo/testify,andymoon/testify,embroker/testify,yxd-hde/testify,roth1002/testify,wallclockbuilder/testify,brahmaroutu/testify,stretchr/testify,betable/testify,dvln/testify,codygibb/testify