make hgrc man page tell about ~/.hgrc on Windows

doc/hgrc.5.txt

@@ -17,37 +17,50 b' FILES'
 
 Mercurial reads configuration data from several files, if they exist.
 The names of these files depend on the system on which Mercurial is
-installed. Windows registry keys contain PATH-like strings, every
-part must reference a Mercurial.ini file or be a directory where *.rc
-files will be read.
+installed.  *.rc files from a single directory are read in
+alphabetical order, later ones overriding earlier ones.  Where
+multiple paths are given below, settings from later paths override
+earlier ones.
 
-(Unix)    <install-root>/etc/mercurial/hgrc.d/*.rc::
-(Unix)    <install-root>/etc/mercurial/hgrc::
+(Unix) <install-root>/etc/mercurial/hgrc.d/*.rc::
+(Unix) <install-root>/etc/mercurial/hgrc::
     Per-installation configuration files, searched for in the
-    directory where Mercurial is installed.  For example, if installed
-    in /shared/tools, Mercurial will look in
-    /shared/tools/etc/mercurial/hgrc.  Options in these files apply to
-    all Mercurial commands executed by any user in any directory.
+    directory where Mercurial is installed.  <install-root> is the
+    parent directory of the hg executable (or symlink) being run.
+    For example, if installed in /shared/tools/bin/hg, Mercurial will
+    look in /shared/tools/etc/mercurial/hgrc.  Options in these files
+    apply to all Mercurial commands executed by any user in any
+    directory.
 
-(Unix)    /etc/mercurial/hgrc.d/*.rc::
-(Unix)    /etc/mercurial/hgrc::
-(Windows) HKEY_LOCAL_MACHINE\SOFTWARE\Mercurial::
-  or::
-(Windows) C:\Mercurial\Mercurial.ini::
+(Unix) /etc/mercurial/hgrc.d/*.rc::
+(Unix) /etc/mercurial/hgrc::
     Per-system configuration files, for the system on which Mercurial
     is running.  Options in these files apply to all Mercurial
     commands executed by any user in any directory.  Options in these
     files override per-installation options.
 
-(Unix)    $HOME/.hgrc::
-(Windows) C:\Documents and Settings\USERNAME\Mercurial.ini::
-(Windows) $HOME\Mercurial.ini::
-    Per-user configuration file, for the user running Mercurial.
-    Options in this file apply to all Mercurial commands executed by
-    any user in any directory.  Options in this file override
+(Windows) <install-dir>\Mercurial.ini::
+  or else::
+(Windows) HKEY_LOCAL_MACHINE\SOFTWARE\Mercurial::
+  or else::
+(Windows) C:\Mercurial\Mercurial.ini::
+    Per-installation/system configuration files, for the system on
+    which Mercurial is running.  Options in these files apply to all
+    Mercurial commands executed by any user in any directory.
+    Registry keys contain PATH-like strings, every part of which must
+    reference a Mercurial.ini file or be a directory where *.rc files
+    will be read.
+
+(Unix) $HOME/.hgrc::
+(Windows) %HOME%\Mercurial.ini::
+(Windows) %HOME%\.hgrc::
+(Windows) %USERPROFILE%\Mercurial.ini::
+(Windows) %USERPROFILE%\.hgrc::
+    Per-user configuration file(s), for the user running Mercurial.
+    On Windows 9x, %HOME% is replaced by %APPDATA%.
+    Options in these files apply to all Mercurial commands executed
+    by this user in any directory.  Options in thes files override
     per-installation and per-system options.
-    On Windows system, one of these is chosen exclusively according
-    to definition of HOME environment variable.
 
 (Unix, Windows) <repo>/.hg/hgrc::
     Per-repository configuration options that only apply in a