add possibility to download compose file

.gitignore

@@ -1,3 +1,3 @@
 data/*
-.env
+.env*
 docker-compose.override.yml

TODO.md

@@ -0,0 +1,32 @@
+# TODO
+
+## easy cert revocation
+
+here comes an example for watching file changes  
+the idea is to extend the step-ca container to be able to revoke certificates easily.  
+not that i think this is needed 0:-)
+
+source: https://stackoverflow.com/questions/22884580/bash-a-way-to-watch-files-for-changes#22885210
+
+```bash
+#!/bin/bash
+
+watched_files=$@  # pass watched files as cmd line arguments
+
+if [ -z "$watched_files" ]; then
+  echo "Nothing to watch, abort"
+  exit
+else
+  echo "watching: $watched_files"
+fi
+
+previous_checksum="dummy"
+while [ 1 ]; do
+  checksum=$(md5sum $watched_files | md5sum)
+  if [ "$checksum" != "$previous_checksum" ]; then
+    echo "None shall pass!"  # do your stuff here
+  fi
+  previous_checksum="$checksum"
+  sleep 1
+done
+```

setup.sh

@@ -2,20 +2,44 @@
 # env setup script for step-ca docker compose
 # 2023-01-06 by dede & dany
 
-echo "step-ca docker compose setup"
-echo "> env setup for step-ca with docker compose..."
+# variables setup
+PROJECT_NAME=step-ca
+#COMPOSE_DOWNLOAD_URL=
+
+# starting the setup
+echo "$PROJECT_NAME docker compose setup"
+echo "> env setup for $PROJECT_NAME with docker compose"
+
+# check for existing compose file to not break an existing setup
+if [ -n "$COMPOSE_DOWNLOAD_URL" ]; then
+  if [[ -f "docker-compose.yml" ]]; then
+    echo "> docker-compose.yml file already exists. setup will not run"
+    exit 1
+  else
+    echo "> downloading docker-compose.yml file from $COMPOSE_DOWNLOAD_URL"
+    wget -O docker-compose.yml "$COMPOSE_DOWNLOAD_URL"
+  fi
+fi
 
 # check for existing .env file to not break an existing setup
 if [[ -f .env ]]; then
   echo "> .env file already exists. setup will not run. either rename or delete it first."
-  exit 1
+  echo -n "do you want to continue anyway and create a new .env file? [y/N]: "
+  read -r continue
+  if [[ $continue =~ ^([yY])$ ]]; then
+    mv ".env" ".env_backup"
+    echo "> saved existing .env file to .env_backup"
+  else
+    exit 1
+  fi
 elif [[ ! -f env.sample ]]; then
   echo "> env.sample file is missing. cannot run."
   exit 2
 fi
 
 # create .env file
-echo -e "# file generated by ${0##*/} on $(date +"%F %H:%M") by $USER\n" > .env
+echo -e "# env file for $PROJECT_NAME compose project" > .env
+echo -e "# generated by ${0##*/} on $(date +"%F %H:%M") by $USER\n" >> .env
 
 # step through the list of lines and ask for each key to use default value or set value
 # for each line in configfile