[mod] reduce enviroment variables in shell scripts to what is needed

Not all settings from the 'brand:' section of the YAML files are needed in the
shell scripts.  This patch reduce the variables in ./utils/brand.env to what is
needed.  The following ('brand:' settings) can be removed from this file:

- ISSUE_URL
- DOCS_URL
- PUBLIC_INSTANCES
- WIKI_URL

Tasks running outside of an *installed instance*, need the following settings
from the YAML configuration:

- GIT_URL            <--> brand.git_url
- GIT_BRANCH         <--> brand.git_branch
- SEARX_URL          <--> server.base_url  (aka PUBLIC_URL)
- SEARX_PORT         <--> server.port
- SEARX_BIND_ADDRESS <--> server.bind_address

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

utils/morty.sh

@@ -12,7 +12,6 @@ source "${REPO_ROOT}/utils/lib_install.sh"
 
 MORTY_LISTEN="${MORTY_LISTEN:-127.0.0.1:3000}"
 PUBLIC_URL_PATH_MORTY="${PUBLIC_URL_PATH_MORTY:-/morty/}"
-
 PUBLIC_URL_MORTY="${PUBLIC_URL_MORTY:-$(echo "$PUBLIC_URL" |  sed -e's,^\(.*://[^/]*\).*,\1,g')${PUBLIC_URL_PATH_MORTY}}"
 
 # shellcheck disable=SC2034
@@ -111,7 +110,7 @@ info_searx() {
     # shellcheck disable=SC1117
     cat <<EOF
 To activate result and image proxy in SearXNG read:
-  ${DOCS_URL}/admin/morty.html
+  https://searxng.github.io/searxng/admin/morty.html
 Check settings in file ${SEARX_SETTINGS_PATH} ...
   result_proxy:
       url : ${PUBLIC_URL_MORTY}