Remove default envs from Docker, update compose & docs

[docker] removed mandatory env variables from Docker image creation removing default values
[docker] updated docker compose example file
[docs] updated docs

docker/Dockerfile

@@ -67,10 +67,7 @@ ENV UID=1000 \
     DB_HOST="postgres" \
     DB_PORT=5432 \
     DB_USER="endurain" \
-    DB_PASSWORD="changeme" \
     DB_DATABASE="endurain" \
-    SECRET_KEY="changeme" \
-    FERNET_KEY="changeme" \
     ALGORITHM="HS256" \
     ACCESS_TOKEN_EXPIRE_MINUTES=15 \
     REFRESH_TOKEN_EXPIRE_DAYS=7 \
@@ -78,8 +75,6 @@ ENV UID=1000 \
     JAEGER_HOST="jaeger" \
     JAEGER_PROTOCOL="http" \
     JAGGER_PORT=4317 \
-    ENDURAIN_HOST="http://localhost:8080" \
-    GEOCODES_MAPS_API="changeme" \
     BEHIND_PROXY=false \
     ENVIRONMENT="production"