Doc: tweak installation doc edits made by commit 76c2af92.

We don't consider that building with MinGW is deprecated,
so adjust some places that gave that impression.
Per discussion with Peter Eisentraut.

Discussion: https://postgr.es/m/4a023388-8652-fea0-a0b4-35ad5e734e9a@2ndquadrant.com

doc/src/sgml/installation.sgml

@@ -15,16 +15,20 @@ documentation.  See standalone-profile.xsl for details.
   <primary>installation</primary>
  </indexterm>
 
+ <!-- See also the version of this text in standalone-install.xml -->
  <para>
   This chapter describes the installation of
   <productname>PostgreSQL</productname> using the source code
   distribution.  If you are installing a pre-packaged distribution,
   such as an RPM or Debian package, ignore this chapter
   and read the packager's instructions instead.
-  Also, this chapter does not describe the preferred way to install
-  <productname>PostgreSQL</productname> on Microsoft
-  Windows<phrase condition="standalone-ignore"> (for that, see
-  <xref linkend="install-windows"/>)</phrase>.
+ </para>
+
+ <para>
+  If you are building <productname>PostgreSQL</productname> for Microsoft
+  Windows, read this chapter if you intend to build with MinGW or Cygwin;
+  but if you intend to build with Microsoft's <productname>Visual
+  C++</productname>, see <xref linkend="install-windows"/> instead.
  </para>
 
  <sect1 id="install-short">
@@ -2484,9 +2488,6 @@ xcodebuild -version -sdk macosx Path
     The MinGW build procedure uses the normal build system described in
     this chapter; the Visual C++ build works completely differently
     and is described in <xref linkend="install-windows"/>.
-    The Visual C++ build is recommended, as it is fully native and uses no
-    additional software like MinGW.  A ready-made installer is available on
-    the main PostgreSQL web site.
    </para>
 
    <para>

doc/src/sgml/standalone-install.xml

@@ -9,11 +9,19 @@ in the stand-alone version.
 <article id="installation">
  <title><productname>PostgreSQL</productname> Installation from Source Code</title>
 
+ <!-- This text replaces the introductory text of installation.sgml -->
  <para>
   This document describes the installation of
   <productname>PostgreSQL</productname> using this source code distribution.
  </para>
 
+ <para>
+  If you are building <productname>PostgreSQL</productname> for Microsoft
+  Windows, read this document if you intend to build with MinGW or Cygwin;
+  but if you intend to build with Microsoft's <productname>Visual
+  C++</productname>, see the main documentation instead.
+ </para>
+
  <xi:include href="postgres.sgml" xpointer="install-short" xmlns:xi="http://www.w3.org/2001/XInclude"/>
  <xi:include href="postgres.sgml" xpointer="install-requirements" xmlns:xi="http://www.w3.org/2001/XInclude"/>
  <xi:include href="postgres.sgml" xpointer="install-procedure" xmlns:xi="http://www.w3.org/2001/XInclude"/>