docs - clarify gpcopy supported greenplum versions (#10621)

* docs - clarify gpcopy supported greenplum versions

* use or later rather than +

gpdb-doc/dita/admin_guide/managing/gpcopy-migrate.xml

@@ -9,7 +9,9 @@
       a high-performance utility that can copy metadata and data from one Greenplum database to
       another Greenplum database. You can migrate the entire contents of a database, or just
       selected tables. The clusters can have different Greenplum Database versions. For example, you
-      can use <codeph>gpcopy</codeph> to migrate data from Greenplum 5 to Greenplum 6.</p>
+      can use <codeph>gpcopy</codeph> to migrate data from a Greenplum Database version 4.3.26
+      (or later) system to a 5.9 (or later) or a 6.x Greenplum system, or from a Greenplum Database
+      version 5.9+ system to a Greenplum 6.x system.</p>
     <note> The <codeph>gpcopy</codeph> utility is available as a separate download for the
       commercial release of Pivotal Greenplum Database. See the <xref
         href="https://gpdb.docs.pivotal.io/gpcopy" format="html" scope="external">Pivotal gpcopy

gpdb-doc/dita/install_guide/migrate.xml

@@ -283,7 +283,8 @@ SELECT '20190905 140000'::timestamp ;</codeblock></p></li>
           <codeph>gpbackup</codeph> or <codeph>gprestore</codeph> filter options to omit schemas or
         tables that cannot be restored without error. </p>
       <p otherprops="pivotal">If you use <codeph>gpcopy</codeph> to migrate data, initiate the
-          <codeph>gpcopy</codeph> operation from the Greenplum 4.3 or 5 cluster. See <xref
+          <codeph>gpcopy</codeph> operation from the Greenplum 4.3.26 (or later) or the
+          5.9 (or later) cluster. See <xref
           scope="peer" href="../admin_guide/managing/gpcopy-migrate.xml">Migrating Data with
           gpcopy</xref> for more information.</p>
       <note type="important">When you restore a backup taken from a Greenplum Database 4.3 or 5