add Dockerfile and tweak deployment instructions

.env.sample

@@ -25,9 +25,9 @@ INFURA_PROJECT_ID=???
 # default is https://test-image.timesafari.app
 #DOWNLOAD_IMAGE_SERVER=test-image.timesafari.app
 
-# default is 3000
+# default is 3002
 #PORT=3000
 
-# default is jdbc:sqlite:./sqlite-db.sqlite
+# default is ./image.sqlite
 # file name also referenced in flyway.conf and in code
-#SQLITE_FILE=./image-db.sqlite
+#SQLITE_FILE=./image.sqlite