add markdown layer

emacs.d/layers/markdown/init.el

@@ -0,0 +1,8 @@
+;; Markdown-mode
+;; https://github.com/jrblevin/markdown-mode
+(use-package markdown-mode
+  :diminish gfm-mode
+  :mode (("README\\.md\\'" . gfm-mode)
+         ("\\.md\\'" . gfm-mode)
+         ("\\.markdown\\'" . gfm-mode))
+  :init (setq markdown-command "multimarkdown"))