Update README.md

Author: hsbt

README.md

@@ -1,8 +1,9 @@
 # Weakref
 
-Welcome to your new gem! In this directory, you'll find the files you need to be able to package up your Ruby library into a gem. Put your Ruby code in the file `lib/weakref`. To experiment with that code, run `bin/console` for an interactive prompt.
+Weak Reference class that allows a referenced object to be
+garbage-collected.
 
-TODO: Delete this and the text above, and describe your gem
+A WeakRef may be used exactly like the object it references.
 
 ## Installation
 
@@ -22,7 +23,14 @@ Or install it yourself as:
 
 ## Usage
 
-TODO: Write usage instructions here
+```ruby
+foo = Object.new            # create a new object instance
+p foo.to_s                  # original's class
+foo = WeakRef.new(foo)      # reassign foo with WeakRef instance
+p foo.to_s                  # should be same class
+GC.start                    # start the garbage collector
+p foo.to_s                  # should raise exception (recycled)
+```
 
 ## Development
 
@@ -32,4 +40,4 @@ To install this gem onto your local machine, run `bundle exec rake install`. To
 
 ## Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/hsbt/weakref.
+Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/weakref.