Try to emphasis user input

ssh/yubibug.md

@@ -11,10 +11,10 @@ Let's try it. For this demo, I'll let the Yubikey generate GnuPG's keys. This is
 
 Let's make things clear :
 
-    $ rm -R .gnupg
-    * rm -R .ssh
-    $ ykman openpgp reset
-    WARNING! This will delete all stored OpenPGP keys and data and restore factory settings? [y/N]: y
+    $ **rm -R .gnupg**
+    * **rm -R .ssh**
+    $ **ykman openpgp reset**
+    WARNING! This will delete all stored OpenPGP keys and data and restore factory settings? [y/N]: **y**
     Resetting OpenPGP data, don't remove your YubiKey...
     Success! All data has been cleared and default PINs are set.
     PIN:         123456