chore(docs): format keyboard shortcut

src/public/app/doc_notes/en/User Guide/User Guide/Theme development/Creating a custom theme.html

@@ -75,7 +75,8 @@
         </p>
         <h2>Step 5. Making changes</h2>
         <p>Simply go back to the note and change according to needs. To apply the
-          changes to the current window, press Ctrl+Shift+R to refresh.</p>
+          changes to the current window, press <kbd>Ctrl</kbd>+<kbd>Shift</kbd>+<kbd>R </kbd> to
+          refresh.</p>
         <p>It's a good idea to keep two windows, one for editing and the other one
           for previewing the changes.</p>
       </div>