Clarify that /etc/crontab is the system crontab.

Submitted by:	Benjamin Kaduk <kaduk@mit.edu>

en_US.ISO8859-1/books/handbook/config/chapter.xml

@@ -520,8 +520,8 @@ run_rc_command "$1"</programlisting>
 	<username>root</username>.</para>
     </note>
 
-    <para>Let us take a look at <filename>/etc/crontab</filename>
-      (the system crontab):</para>
+    <para>Let us take a look at <filename>/etc/crontab</filename>,
+      the system crontab:</para>
 
     <programlisting># /etc/crontab - root's crontab for &os;
 #
@@ -540,8 +540,8 @@ HOME=/var/log
 
     <calloutlist>
       <callout arearefs="co-comments">
-	<para>Like most &os; configuration files, the
-	  <literal>#</literal> character represents a comment.  A
+	<para>Like most &os; configuration files, lines that begin with the
+	  <literal>#</literal> character are comments.  A
 	  comment can be placed in the file as a reminder of what and
 	  why a desired action is performed. Comments cannot be on the
 	  same line as a command or else they will be interpreted as
@@ -608,8 +608,8 @@ HOME=/var/log
     <para>This is the basic setup for every
       <filename>crontab</filename> file, although there is one thing
       different about this one.  Field number six, where we specified
-      the username, only exists in the system
-      <filename>/etc/crontab</filename>.  This field should be
+      the username, only exists in the system <filename>crontab</filename>.
+      This field should be
       omitted for individual user <filename>crontab</filename>
       files.</para>