[tldoc] doc update for windows %systemdrive%

[Karl Berry]

Due to Windows issues, we felt we should change the default directory on
Windows to use %SystemDrive% instead of %PROGRAMFILES%.  In addition, we
felt the default should always be to install for the current user only,
and make system-wide installation an explicit option.
These seemed like more reliable defaults.

Unfortunately this means four small changes to the documentation.
I sincerely hope this will be the end.

FWIW, as far as I'm concerned it is still the documentation translations
which are the only thing that need to be finished before we make the
release.  So please try to get them in.

Thanks,
karl


--- texlive-en.tex	(revision 15413)
+++ texlive-en.tex	(working copy)
@@ -748,7 +748,7 @@
 The default layout is described in section~\ref{sec:texmftrees},
 \p.\pageref{sec:texmftrees}. The default location of
 \dirname{TEXDIR} is different between Windows
-(|%PROGRAMFILES%\texlive\2009|) and Unix
+(|%SystemDrive%\texlive\2009|) and Unix
 (\dirname{/usr/local/texlive/2009}).
 
 The main reason to change this default is if you lack write permission
@@ -1104,7 +1104,7 @@
 This is already mentioned implicitly in section~\ref{sec:texmftrees}:
 \dirname{TEXMFLOCAL} (by default,
 \dirname{/usr/local/texlive/texmf-local} or
-\verb|C:\Program Files\texlive\texmf-local|)
+\verb|%SystemDrive%\texlive\texmf-local|)
 is intended for system-wide local fonts and macros; and
 \dirname{TEXMFHOME} (by default, \dirname{$HOME/texmf} or
 \verb|%USERPROFILE%\texmf|), is for personal fonts and macros.  These
@@ -1582,14 +1582,14 @@
 administrator is the rule, not the exception. Nevertheless, we have made
 an effort to make \TL{} installable without administrative privileges.
 
-If the user is an administrator, shortcuts are created for all users,
+If the user is an administrator, there is an option to install for all
+users.  If this option is chosen, shortcuts are created for all users,
 and the system environment is modified. Otherwise, shortcuts and menu
 entries are created for the current user, and the user environment is
-modified.  Use the \optname{non-admin} option to \prog{install-tl} if
-you prefer per-user settings even as an administrator.
+modified.
 
 Regardless of administrator status, the default root of \TL{} proposed
-by the installer is always under \verb|%PROGRAMFILES%|. The installer
+by the installer is always under \verb|%SystemDrive%|. The installer
 always tests whether the root is writable for the current user.
 
 A problem may arise if the user is not an administrator and \TeX{}