Removed dbm from ruby repo

Author: hsbt

doc/maintainers.rdoc

@@ -312,10 +312,6 @@ Yukihiro Matsumoto (matz)
   _unmaintained_
   https://github.com/ruby/date
   https://rubygems.org/gems/date
-[ext/dbm]
-  _unmaintained_
-  https://github.com/ruby/dbm
-  https://rubygems.org/gems/dbm
 [ext/etc]
   Ruby core team
   https://github.com/ruby/etc

doc/standard_library.rdoc

@@ -83,7 +83,6 @@ WeakRef:: Allows a referenced object to be garbage-collected
 BigDecimal:: Provides arbitrary-precision floating point decimal arithmetic
 Date:: A subclass of Object includes Comparable module for handling dates
 DateTime:: Subclass of Date to handling dates, hours, minutes, seconds, offsets
-DBM:: Provides a wrapper for the UNIX-style Database Manager Library
 Digest:: Provides a framework for message digest libraries
 Etc:: Provides access to information typically stored in UNIX /etc directory
 Fcntl:: Loads constants defined in the OS fcntl.h C header file