README.win32: [DOC] added modeline [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67008 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2019-02-05 06:00:25 +00:00 · 2019-02-05 06:00:25 +00:00 · af479d54dc
--- a/win32/README.win32
+++ b/win32/README.win32
@ -1,3 +1,5 @@
+# -*- rdoc -*-
+
 = How to build ruby using Visual C++

 == Requirement