[md][box][localassembler] fix comment in self update

dumux/multidomain/subdomainboxlocalassembler.hh

@@ -554,12 +554,10 @@ public:
                 this->couplingManager().updateCouplingContext(domainI, *this, domainJ, globalJ, priVarsJ, pvIdx);
             }
 
-            // restore original state of the flux vars cache and/or vol vars in case of global caching.
-            // This has to be done in order to guarantee that everything is in an undeflected
-            // state before the assembly of another element is called. In the case of local caching
-            // this is obsolete because the local views used here go out of scope after this.
-            // We only have to do this for the last primary variable, for all others the flux var cache
-            // is updated with the correct element volume variables before residual evaluations
+            // Restore original state of the flux vars cache and/or vol vars.
+            // This has to be done in case they depend on variables of domainJ before
+            // we continue with the numeric derivative w.r.t the next globalJ. Otherwise,
+            // the next "origResidual" will be incorrect.
             updateSelf();
         }
     }