Updated the html textarea editor code shortcut

refs https://github.com/TryGhost/Team/issues/1206

- the editor will behave like the main Ghost editor and will wrap text between backticks with a <code> tag

ghost/admin/lib/koenig-editor/addon/components/koenig-basic-html-textarea.js

@@ -23,7 +23,7 @@ const UNDO_DEPTH = 50;
 const SPECIAL_MARKUPS = {
     S: '~~',
     CODE: {
-        char: '{', // this is different because we use <code> to represent {} replacements
+        char: '`',
         replace: false
     },
     SUP: '^',