Add note about DDF to docs titles on 1.11 and main

The Quarkus documentation repo on GitLab has been set up to pull in shared content that is reused across docs sets on several Red Hat Runtimes products.
The shared content is maintained and modified in the mw-shared-modules repository on GitHub and set up to automatically sync to our repo once a day using an automated script running on a Jenkins server (we'll discuss this part at a later point.)

Specifically, for the Quarkus docs repo we sync shared modules from the runtimes-common directory in the mw-shared-modules repo to the identically named runtimes-common directory in the Quarkus docs repo.

Any modules in the runtimes-common/ directory can be used in the same way as our regular doc modules that we have in the modules/ directory.
The only exception is that the modules in the runtimes-common/ directory are meant to be used as they are, and we should not edit them in our repository (This is because any edits that you make to them inside our repo will get overwritten next time the sync script runs). (If you need to edit the modules you need to file a Pull request for the edits in the mw-shared-modules repository on GitHub. We'll cover how to properly make changes to these modules on a separate occasion, too.)

The runtimes-common directory is symbolically linked inside the modules/ directory where we store the rest of our doc modules.

So, all you have to do to include a module from runtimes-common in one of your titles is to use a regular include statement, just as you'd do for any other module, but with a slightly different path (see include example).

For example, to include the DDF module in a master.adoc file of any of our guides in the product docs set, just add the following to the master.adoc file:

include::modules/runtimes-common/proc_providing_direct_documentation_feedback.adoc[leveloffset=+1]