tooling box: simplify build enviroments

- no more need for a .config.mk
- docs: use searx.brands environment
- searx.sh, filtron.sh & morty.sh are sourcing utils/brand.env

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

utils/templates/etc/apache2/sites-available/morty.conf

@@ -23,6 +23,6 @@ ProxyPreserveHost On
     # needed by searx to render correct *Search URL* in the *Link* box and
     # *saved preference*.
 
-    # RequestHeader set Host ${PUBLIC_URL_PATH_MORTY}
+    # RequestHeader set Host ${PUBLIC_HOST}
 
 </Location>