update song.py as per code, add missing vars in sample config, fix pm/tag logger bug.

sample-config.env

@@ -20,6 +20,11 @@ DB_URL=
 # Mongo DB cluster URL
 
 
+# EXTRA_MODULES_REPO=
+# To add extra modules or mini bots that require stuff in ub.
+# Only For Advance Users.
+
+
 # FBAN_LOG_CHANNEL=
 # Optional FedBan Proof and logs.
 
@@ -38,6 +43,11 @@ LOG_CHAT=
 # Bot logs chat/channel
 
 
+# MESSAGE_LOGGER_CHAT=
+# For PM and Tag logger
+# Defaults to sending in Log Channel Above
+
+
 OWNER_ID=
 # Your user ID