Added a section on startup in the README.md (#507)

Reworked the index.md
- removed commented out text

Minor restructuring of the README.md

---------

Co-authored-by: Tristan Nolde <tristan.nolde@yahoo.de>

docker-compose.yml

@@ -67,7 +67,7 @@ services:
     depends_on:
     - postgres
     ports:
-    - ${HTTP_PORT}:${HTTP_PORT}
+    - ${HTTP_PORT:-error}:${HTTP_PORT:-error}
     environment:
       PYTHON_POSTGRES_USERNAME: ${PYTHON_POSTGRES_USERNAME:-postgres}
       PYTHON_POSTGRES_PASSWORD: ${PYTHON_POSTGRES_PASSWORD:?error}
@@ -76,6 +76,6 @@ services:
       PYTHON_POSTGRES_PORT: ${PYTHON_POSTGRES_PORT:-5432}
       PYTHON_DASH_LOGIN_PW: ${PYTHON_DASH_LOGIN_PW}
       PYTHON_DASH_LOGIN_USERNAME: ${PYTHON_DASH_LOGIN_USERNAME}
-      DASH_URL_BASE_PATHNAME: /transparenzregister/
-      PORT: ${HTTP_PORT}
+      DASH_URL_BASE_PATHNAME: ${DASH_URL_BASE_PATHNAME:-/transparenzregister/}
+      PORT: ${HTTP_PORT:-error}
       HOST: 0.0.0.0