THRIFT-2407 use markdown (rename README => README.md)
Patch: Roger Meier
diff --git a/lib/rb/thrift.gemspec b/lib/rb/thrift.gemspec
index a91ea07..43e5a7f 100644
--- a/lib/rb/thrift.gemspec
+++ b/lib/rb/thrift.gemspec
@@ -23,7 +23,7 @@
   s.test_files = Dir.glob("{test,spec,benchmark}/**/*")
   s.executables =  Dir.glob("{bin}/**/*")
 
-  s.extra_rdoc_files  = %w[README] + Dir.glob("{ext,lib}/**/*.{c,h,rb}")
+  s.extra_rdoc_files  = %w[README.md] + Dir.glob("{ext,lib}/**/*.{c,h,rb}")
 
   s.require_paths = %w[lib ext]