doc: fix typo in release notes

Backpatch through 8.4

Per suggestion by Amit Langote

Author: bmomjian

doc/src/sgml/release-8.4.sgml

@@ -91,8 +91,8 @@
 
     <listitem>
      <para>
-      Fix rare <literal>GROUP BY</> query error caused by improperly processed date type
-      modifiers (Tom Lane)
+      Fix rare <literal>GROUP BY</> query error caused by improperly
+      processed data type modifiers (Tom Lane)
      </para>
     </listitem>
 

doc/src/sgml/release-9.0.sgml

@@ -105,8 +105,8 @@
 
     <listitem>
      <para>
-      Fix rare <literal>GROUP BY</> query error caused by improperly processed date type
-      modifiers (Tom Lane)
+      Fix rare <literal>GROUP BY</> query error caused by improperly
+      processed data type modifiers (Tom Lane)
      </para>
     </listitem>
 

doc/src/sgml/release-9.1.sgml

@@ -111,8 +111,8 @@
 
     <listitem>
      <para>
-      Fix rare <literal>GROUP BY</> query error caused by improperly processed date type
-      modifiers (Tom Lane)
+      Fix rare <literal>GROUP BY</> query error caused by improperly
+      processed data type modifiers (Tom Lane)
      </para>
     </listitem>
 

doc/src/sgml/release-9.2.sgml

@@ -140,8 +140,8 @@
 
     <listitem>
      <para>
-      Fix rare <literal>GROUP BY</> query error caused by improperly processed date type
-      modifiers (Tom Lane)
+      Fix rare <literal>GROUP BY</> query error caused by improperly
+      processed data type modifiers (Tom Lane)
      </para>
     </listitem>