Made the link https and moved default value into setting

docker-compose.yml

@@ -442,9 +442,8 @@ services:
       #
       # At which interval does the background task sync in milliseconds.
       # The format must be as specified in:
-      # http://bunkat.github.io/later/parsers.html#text
-      # The default is "every 1 hour"
-      - LDAP_BACKGROUND_SYNC_INTERVAL=''
+      # https://bunkat.github.io/later/parsers.html#text
+      - LDAP_BACKGROUND_SYNC_INTERVAL='every 1 hour'
       #
       #- LDAP_BACKGROUND_SYNC_KEEP_EXISTANT_USERS_UPDATED=false
       #