Added yaml to Markdown fenced languages

.vimrc

@@ -32,7 +32,7 @@ syntax enable
 filetype plugin on
 
 " Native Markdown syntax highlighting for specified languages
-let g:markdown_fenced_languages = ['html', 'python', 'sh', 'vim']
+let g:markdown_fenced_languages = ['html', 'python', 'sh', 'vim', 'yaml']
 
 " Open my personal helpfile
 nmap <leader>h :e $HOME/.vim/vim-keys-help.md<CR>