Slight cleanup of the collection of READMEs, INSTALLs and NOTES

README is a fairly independent document, and so is INSTALL.  NOTES are
merely addendums to INSTALL.  Therefore , INSTALL.DJGPP and
README.PERL get renamed to NOTES.DJGPP and NOTES.PERL.

Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/NOTES.WIN b/NOTES.WIN
index bed5037..a2e9120 100644
--- a/NOTES.WIN
+++ b/NOTES.WIN
@@ -5,10 +5,13 @@
  Requirement details for native (Visual C++) builds
  --------------------------------------------------
 
+ In addition to the requirements and instructions listed in INSTALL,
+ this are required as well:
+
  - You need Perl.  We recommend ActiveState Perl, available from
    http://www.activestate.com/ActivePerl.
    You also need the perl module Text::Template, available on CPAN.
-   Please read README.PERL for more information.
+   Please read NOTES.PERL for more information.
 
  - You need a C compiler.  OpenSSL has been tested to build with these: