DOC: added PGPRO release notes for 10.3.1 release

Author: Liudmila Mantrova

doc/src/sgml/release-pro-10.sgml

@@ -1,5 +1,34 @@
 <!-- doc/src/sgml/release-pro-10.sgml -->
 <!-- See header comment in release.sgml about typical markup -->
+<sect1 id="release-pro-10-3-1">
+  <title>Postgres Pro Standard 10.3.1</title>
+  <formalpara>
+    <title>Release Date:</title>
+    <para>2018-03-01</para>
+  </formalpara>
+  <sect2>
+    <title>Overview</title>
+    <para>This release is based on <productname>PostgreSQL</productname> 10.3
+      and <productname>Postgres Pro Standard</productname> 10.2.1. All
+      changes are inherited from <productname>PostgreSQL</productname> 10.3 and are listed in
+      <link linkend="release-10-3"><productname>PostgreSQL</productname> 10.3 Release Notes</link>.
+    </para>
+  </sect2>
+  <sect2>
+    <title>Migration to Version 10.3.1</title>
+
+    <para>If you are upgrading from a <productname>Postgres Pro Standard</productname> version
+      based on the same <productname>PostgreSQL</productname> major release,
+      it is enough to install the new version into your current installation directory.
+      </para>
+    <para>To migrate from <productname>PostgreSQL</productname> or
+      <productname>Postgres Pro Standard</productname> versions based on
+      any previous <productname>PostgreSQL</productname> major release, see the instructions
+      in <link linkend="release-pro-10-2-1">Postgres Pro Standard 10.2.1 Release Notes</link>.
+    </para>
+
+  </sect2>
+</sect1>
 <sect1 id="release-pro-10-2-1">
   <title>Postgres Pro Standard 10.2.1</title>
   <formalpara>