Add explanation for deactivating a group of deprecated modules

Author: victoryforce

src/libs/modulegroups.c

@@ -1780,10 +1780,16 @@ void init_presets(dt_lib_module_t *self)
   dt_lib_presets_add(_("search only"),
                      self->plugin_name, self->version(), tx, strlen(tx), TRUE, 0);
 
+  // There is no need for the deprecated modules group now, as there have been
+  // no new module deprecations for a long time. The group is not for access
+  // to all once deprecated modules, it should only contain deprecated modules
+  // temporarily (planned for 1 year) to prepare users of these modules for
+  // the need to learn the replacement modules.
+  // We are not removing the following code, just commenting it out for possible
+  // updating if we decide to deprecate any modules again in the future.
 #if 0
-  // this is a special preset for all newly deprecated modules
-  // so users still have a chance to access them until next release (with warning messages)
-  // this modules are deprecated in 3.4 and should be removed from this group in 3.8 (1 year later)
+  // This is a special preset for all newly deprecated modules, so users still
+  // have a chance to access them until next release (with warning messages)
   SNQA();
   SMG(C_("modulegroup", "deprecated"), "basic");
   // these modules are deprecated in 4.4 and should be removed in 4.8 (1 year later)