Tailored instructions do not say to update /etc/php5/apache/php.ini.

Step 8 is:

Update /etc/php5/cli/php.ini and change the line
zend_extension = /usr/lib64/php5/extensions/xdebug.so

Now - it's obviously trivial to add the extension to the /etc/php5/apache/php.ini file - but when you're just copying the instructions you may not notice you've done this.

It's traceable - but not immediately obvious that this is needed as the output of 'php -m' shows the module as available - but then the main xdebug section is missing from phpinfo() output.

If there is a reason to keep xdebug for the cli only initially at least there should be a note in the tailored instructions to update /etc/php5/apache/php.ini if xdebug is needed in a browser.