docs: add ?

Author: kenjis

user_guide_src/source/installation/troubleshooting.rst

@@ -37,7 +37,7 @@ REQUEST_URI variable needed to serve search-engine friendly URLs. As a
 first step, open your **app/Config/App.php** file and look for
 the URI Protocol information. It will recommend that you try a couple of
 alternate settings. If it still doesn't work after you've tried this
-you'll need to force CodeIgniter to add a question mark to your URLs. To
+you'll need to force CodeIgniter to add a question mark (``?``) to your URLs. To
 do this open your **app/Config/App.php** file and change this:
 
 .. literalinclude:: troubleshooting/001.php