Update obsoleted URLs of supported platforms [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63666 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

README.ja.md

@@ -18,7 +18,7 @@ Rubyはテキスト処理関係の能力などに優れ，Perlと同じくらい
 *   ダイナミックローディング (アーキテクチャによる)
 *   移植性が高い．多くのUnix-like/POSIX互換プラットフォーム上で動くだけでなく，Windows， macOS，
     Haikuなどの上でも動く cf.
-    https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/SupportedPlatformsJa
+    https://github.com/ruby/ruby/blob/trunk/doc/contributing.rdoc#platform-maintainers
 
 
 ## 入手法

README.md

@@ -20,7 +20,7 @@ extensible.
 *   Dynamic Loading of Object Files (on some architectures)
 *   Highly Portable (works on many Unix-like/POSIX compatible platforms as
     well as Windows, macOS, Haiku, etc.) cf.
-    https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/SupportedPlatforms
+    https://github.com/ruby/ruby/blob/trunk/doc/contributing.rdoc#platform-maintainers
 
 
 ## How to get Ruby