Added the upstream repositories to default gems.

doc/maintainers.rdoc

@@ -186,20 +186,28 @@ Zachary Scott (zzak)
   https://github.com/ruby/fileutils
 [lib/forwardable.rb]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/forwardable
 [lib/ipaddr.rb]
   Akinori MUSHA (knu)
+  https://github.com/ruby/ipaddr
 [lib/irb.rb, lib/irb/*]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/irb
 [lib/logger.rb]
   Naotoshi Seo (sonots)
+  https://github.com/ruby/logger
 [lib/matrix.rb]
   Marc-Andre Lafortune (marcandre)
+  https://github.com/ruby/matrix
 [lib/mutex_m.rb]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/mutex_m
 [lib/ostruct.rb]
   Marc-Andre Lafortune (marcandre)
+  https://github.com/ruby/ostruct
 [lib/prime.rb]
   Yuki Sonoda (yugui)
+  https://github.com/ruby/prime
 [lib/racc.rb, lib/racc/*]
   Aaron Patterson (tenderlove), Hiroshi SHIBATA (hsbt)
   https://github.com/ruby/racc
@@ -208,21 +216,28 @@ Zachary Scott (zzak)
   https://github.com/ruby/rdoc
 [lib/reline.rb, lib/reline/*]
   aycabta
+  https://github.com/ruby/reline
 [lib/rexml/*]
   Kouhei Sutou (kou)
+  https://github.com/ruby/rexml
 [lib/rss.rb, lib/rss/*]
   Kouhei Sutou (kou)
+  https://github.com/ruby/rss
 [lib/scanf.rb]
   David A. Black (dblack)
   https://github.com/ruby/scanf
 [lib/shell.rb, lib/shell/*]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/shell
 [lib/sync.rb]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/sync
 [lib/thwait.rb]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/thwait
 [lib/tracer.rb]
   Keiju ISHITSUKA (keiju)
+  https://github.com/ruby/tracer
 [lib/webrick.rb, lib/webrick/*]
   Eric Wong (normalperson)
   https://bugs.ruby-lang.org/
@@ -264,6 +279,7 @@ Zachary Scott (zzak)
   https://github.com/ruby/psych
 [ext/racc]
   Aaron Patterson (tenderlove), Hiroshi SHIBATA (hsbt)
+  https://github.com/ruby/racc
 [ext/sdbm]
   Yukihiro Matsumoto (matz)
   https://github.com/ruby/sdbm