Updated readme.
Updated readme.

MWDelaney/bootstrap-3-shortcodes,robbieaverill/php-markdown,filipstefansson/bootstrap-3-shortcodes,jockchou/php-markdown,mariokonrad/php-markdown,filipstefansson/bootstrap-3-shortcodes,Kapeli/php-markdown,itafroma/php-markdown,MWDelaney/bootstrap-3-shortcodes,n054/php-markdown,nazar-pc/php-markdown-next,queirozfcom/php-markdown-with-syntax-highlight,ashur/php-markdown,MWDelaney/bootstrap-3-shortcodes