fix(modules/django-apps): Add descriptions where missing

modules/nixos/django-apps/default.nix

@@ -326,12 +326,18 @@ in
                 type = str;
                 readOnly = true;
                 default = "/var/lib/django-apps/${name}";
+                description = ''
+                  The directory containing the various files necessary for the website to function.
+                '';
               };
 
               sourceDirectory = mkOption {
                 type = str;
                 readOnly = true;
                 default = "${config.baseDirectory}/source";
+                description = ''
+                  The path where the source code of the django application will be stored. It is an absolute path.
+                '';
               };
 
               staticDirectory = mkOption {
@@ -355,6 +361,10 @@ in
           }
         )
       );
+      default = { };
+      description = ''
+        The set of django websites to deploy.
+      '';
     };
   };