bug#26508: another patch for efaq-w32.texi

[Tak Kunihiro]

I think the most appropriate directory to start with by C-x C-f is,
%HOME% directory.  I add a paragraph to do so even with emacs -Q.

--- efaq-w32.texi       2017-04-15 07:41:13.130868400 +0900
+++ efaq-w32-b.texi     2017-04-15 13:29:42.148704100 +0900
@@ -320,6 +320,10 @@
 @file{addpm.exe}, which is usually installed into the same @file{bin}
 directory with @file{emacs.exe}.
 
+You can change directory to start with by @kbd{C-x C-f}.  Set `Start in'
+of the shortcut installed in your Start Menu, for example, to
+environment variable such as @code{%HOME%}.
+
 @node Image support
 @section How do I get image support?
 @cindex images, installing libraries for