fix(shift): off by one typo

LDP/guide/docbook/Bash-Beginners-Guide/chap9.xml

@@ -507,7 +507,7 @@ rm "$QUIT"
 <sect1 id="sect_09_07"><title>The shift built-in</title>
 <sect2 id="sect_09_07_01"><title>What does it do?</title>
 <para>The <command>shift</command> command is one of the Bourne shell built-ins that comes with Bash.  This command takes one argument, a number.  The positional parameters are shifted to the left by this number, <emphasis>N</emphasis>.  The positional parameters from <varname>N+1</varname> to <varname>$#</varname> are renamed to variable names from <varname>$1</varname> to <varname>$# - N+1</varname>.</para>
-<para>Say you have a command that takes 10 arguments, and N is 4, then <varname>$4</varname> becomes <varname>$1</varname>, <varname>$5</varname> becomes <varname>$2</varname> and so on.  <varname>$10</varname> becomes <varname>$7</varname> and the original <varname>$1</varname>, <varname>$2</varname> and <varname>$3</varname> are thrown away.</para>
+<para>Say you have a command that takes 10 arguments, and N is 3, then <varname>$4</varname> becomes <varname>$1</varname>, <varname>$5</varname> becomes <varname>$2</varname> and so on.  <varname>$10</varname> becomes <varname>$7</varname> and the original <varname>$1</varname>, <varname>$2</varname> and <varname>$3</varname> are thrown away.</para>
 <para>If N is zero or greater than <varname>$#</varname>, the positional parameters are not changed (the total number of arguments, see <xref linkend="sect_07_02_01_02" />) and the command has no effect.  If N is not present, it is assumed to be 1.  The return status is zero unless N is greater than <varname>$#</varname> or less than zero; otherwise it is non-zero.</para>
 </sect2>
 <sect2 id="sect_09_07_02"><title>Examples</title>