[DOC] Add win32/README.win32 to .document

see https://github.com/ruby/docs.ruby-lang.org/issues/56 git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63139 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2018-04-12 14:24:06 +00:00 · 2018-04-12 14:24:06 +00:00 · dfeafff30e
--- a/.document
+++ b/.document
@ -28,4 +28,7 @@ COPYING
 COPYING.ja
 CONTRIBUTING.md

+# win32/README.win32 linked from README.md
+win32
+
 doc
--- a/win32/.document
+++ b/win32/.document
@ -0,0 +1 @@
+README.win32