doc: Move DEFAULT parameter on COPY reference page

The DEFAULT parameter seems most similar to the NULL parameter, so
move it next to it, instead of having it at the end of the parameter
list because it was the last one added.

doc/src/sgml/ref/copy.sgml

@@ -36,6 +36,7 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     FREEZE [ <replaceable class="parameter">boolean</replaceable> ]
     DELIMITER '<replaceable class="parameter">delimiter_character</replaceable>'
     NULL '<replaceable class="parameter">null_string</replaceable>'
+    DEFAULT '<replaceable class="parameter">default_string</replaceable>'
     HEADER [ <replaceable class="parameter">boolean</replaceable> | MATCH ]
     QUOTE '<replaceable class="parameter">quote_character</replaceable>'
     ESCAPE '<replaceable class="parameter">escape_character</replaceable>'
@@ -43,7 +44,6 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     FORCE_NOT_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] )
     FORCE_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] )
     ENCODING '<replaceable class="parameter">encoding_name</replaceable>'
-    DEFAULT '<replaceable class="parameter">default_string</replaceable>'
 </synopsis>
  </refsynopsisdiv>
 
@@ -271,6 +271,19 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>DEFAULT</literal></term>
+    <listitem>
+     <para>
+      Specifies the string that represents a default value. Each time the string
+      is found in the input file, the default value of the corresponding column
+      will be used.
+      This option is allowed only in <command>COPY FROM</command>, and only when
+      not using <literal>binary</literal> format.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>HEADER</literal></term>
     <listitem>
@@ -369,19 +382,6 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     </listitem>
    </varlistentry>
 
-   <varlistentry>
-    <term><literal>DEFAULT</literal></term>
-    <listitem>
-     <para>
-      Specifies the string that represents a default value. Each time the string
-      is found in the input file, the default value of the corresponding column
-      will be used.
-      This option is allowed only in <command>COPY FROM</command>, and only when
-      not using <literal>binary</literal> format.
-     </para>
-    </listitem>
-   </varlistentry>
-
    <varlistentry>
     <term><literal>WHERE</literal></term>
     <listitem>