docs: fix CEDefaults/Modules path and document diracInstallOnly

Address PR review: correct the option name to /Resources/Computing/CEDefaults/Modules
in the remaining occurrences, and document GenericOptions = diracInstallOnly to force
the pilot to install the override even when a matching release exists on CVMFS.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: aldbr

docs/source/AdministratorGuide/Systems/WorkloadManagement/Pilots/index.rst

@@ -107,13 +107,17 @@ but similarly a non-released in-development branch can be set.
 
 .. note::
 
-   The SiteDirector reads this option when it builds the pilots. After changing ``/Resources/Computing/CEDefaultsModules`` (or any other pilot configuration), you have to restart the SiteDirector agent for the change to be taken into account by the pilots it submits.
+   The SiteDirector reads this option when it builds the pilots. After changing ``/Resources/Computing/CEDefaults/Modules`` (or any other pilot configuration), you have to restart the SiteDirector agent for the change to be taken into account by the pilots it submits.
 
 DIRAC extensions can be added on the same line after a comma, e.g.:
 
 .. code-block:: bash
 
-   /Resources/Computing/CEDefaultsModules=https://github.com/$DIRAC_test_repo/DIRAC.git:::DIRAC:::$DIRAC_test_branch,https://gitlab.cern.ch/$LHCBDIRAC_repo/LHCbDIRAC.git:::LHCbDIRAC:::$LHCbDIRAC_branch
+   /Resources/Computing/CEDefaults/Modules=https://github.com/$DIRAC_test_repo/DIRAC.git:::DIRAC:::$DIRAC_test_branch,https://gitlab.cern.ch/$LHCBDIRAC_repo/LHCbDIRAC.git:::LHCbDIRAC:::$LHCbDIRAC_branch
+
+.. note::
+
+   If the pilot version (e.g. ``Operations/Default/Pilot/Version``) points to a release that is already available on CVMFS, the pilot will favour that pre-installed release and ignore the ``Modules`` override. To force the pilot to perform the installation from the URL(s) above every time, set ``GenericOptions = diracInstallOnly`` in the same ``/Resources/Computing/CEDefaults`` section.
 
 Pilot Commands
 ==============