fix(conf): auto subscription, batter docs

Co-authored-by: Dmitrii <99872536+ieQu1@users.noreply.github.com>

apps/emqx_auto_subscribe/etc/emqx_auto_subscribe.conf

@@ -1,8 +1,8 @@
 
-## When the device log in successfully,
-## The auto-subscribe will complete the subscription for the device
+## When the device logs in successfully,
+## the auto-subscribe will complete the subscription for the device
 ## according to the preset topics list.
-## Placeholders is supported.
+## Placeholders are supported.
 ##
 ## - ${clientid}
 ## - ${username}