Update the documentation for weakref

doc/maintainers.rdoc

@@ -99,8 +99,6 @@ Zachary Scott (zzak)
   WATANABE Hirofumi (eban)
 [lib/unicode_normalize.rb, lib/unicode_normalize/*]
   Martin J. Dürst
-[lib/weakref.rb]
-  _unmaintained_
 
 === Extensions
 
@@ -261,6 +259,9 @@ Zachary Scott (zzak)
 [lib/yaml.rb, lib/yaml/*]
   Aaron Patterson (tenderlove), Hiroshi SHIBATA (hsbt)
   https://github.com/ruby/yaml
+[lib/weakref.rb]
+  _unmaintained_
+  https://github.com/ruby/weakref
 
 === Extensions
 

doc/standard_library.rdoc

@@ -37,7 +37,6 @@ Time:: Extends the Time class with methods for parsing and conversion
 tmpdir.rb:: Extends the Dir class to manage the OS temporary file path
 TSort:: Topological sorting using Tarjan's algorithm
 un.rb:: Utilities to replace common UNIX commands
-WeakRef:: Allows a referenced object to be garbage-collected
 
 == Extensions
 
@@ -86,6 +85,7 @@ Tracer:: Outputs a source level execution trace of a Ruby program
 URI:: A Ruby module providing support for Uniform Resource Identifiers
 WEBrick:: An HTTP server toolkit for Ruby
 YAML:: Ruby client library for the Psych YAML implementation
+WeakRef:: Allows a referenced object to be garbage-collected
 
 == Extensions