Suggest ./zcutil/fetch-params.sh as well

Once we improve the from-source installation docs to use 'make install', we can
revert this commit.

src/init.cpp

@@ -625,7 +625,7 @@ static void ZC_LoadParams()
         uiInterface.ThreadSafeMessageBox(strprintf(
             _("Cannot find the Zcash network parameters in the following directory:\n"
               "%s\n"
-              "Please run 'zcash-fetch-params' and then restart."),
+              "Please run 'zcash-fetch-params' or './zcutil/fetch-params.sh' and then restart."),
                 ZC_GetParamsDir()),
             "", CClientUIInterface::MSG_ERROR);
         StartShutdown();