Set EJABBERD_OPTS back to "", and use previous flags as example

Also try to clarify distinction between EJABBERD_OPTS and ERLANG_OPTS

ejabberdctl.cfg.example

@@ -109,7 +109,10 @@
 #' ERL_OPTIONS: Additional Erlang options
 #
 # The next variable allows to specify additional options passed to
-# erlang. See erl(1) for more info.
+# all commands using erlang interpreter. This applies to starting
+# ejabberd server itself but also auxiliary commands like for example
+# starting debug shell. See erl(1) for list of commands that can be
+# used here.
 #
 # It might be useful to add "-pa /usr/local/lib/ejabberd/ebin" if you
 # want to add local modules in this path.
@@ -126,10 +129,11 @@
 # ejabberd is started from an init.d script options -noshell and -detached are
 # added implicitly. See erl(1) for more info.
 #
+# For example you can use value "-heart -env HEART_BEAT_TIMEOUT 120 -env ERL_CRASH_DUMP_SECONDS 60"
+#
 # Default: ""
 #
 #EJABBERD_OPTS=""
-EJABBERD_OPTS="-heart -env HEART_BEAT_TIMEOUT 120 -env ERL_CRASH_DUMP_SECONDS 60"
 
 #.
 #' ERLANG_NODE: Erlang node name