utils & Makefile: add .config.mk & .config.sh for searx brands

By isolating the environment of makefiles and bash scripts into .config.mk and
.config.sh it is simple to maintain searx brands by setting some central
environments.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

.config.mk

@@ -0,0 +1,13 @@
+# -*- coding: utf-8; mode: makefile-gmake -*-
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# This environment is used by Makefile targets.  If you not maintain your own
+# searx brand, you normally not need to change the defaults (except SEARX_URL).
+# Compare your settings here with file .config.sh used by the toolboxing in
+# utils.
+
+export SEARX_URL=https://searx.me
+
+export GIT_URL=https://github.com/asciimoo/searx
+export DOCS_URL=https://asciimoo.github.io/searx
+