build cleanups

* update docs to simplify build steps
* Gemfile.lock seemed to have an older version specified
* do not check in the pkg dir

ruby/.gitignore

diff --git a/ruby/.gitignore b/ruby/.gitignore
index 80c978f..93e2450 100644
--- a/ruby/.gitignore
+++ b/ruby/.gitignore
@@ -4,3 +4,4 @@
 lib/google/protobuf_java.jar
 protobuf-jruby.iml
 target/
+pkg/

ruby/Gemfile.lock

diff --git a/ruby/Gemfile.lock b/ruby/Gemfile.lock
index 89deb47..6f34927 100644
--- a/ruby/Gemfile.lock
+++ b/ruby/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    google-protobuf (3.0.0.alpha.2)
+    google-protobuf (3.0.0.alpha.3.1.pre)
 
 GEM
   remote: https://rubygems.org/

ruby/README.md

diff --git a/ruby/README.md b/ruby/README.md
index d2fa76a..9ae3ac3 100644
--- a/ruby/README.md
+++ b/ruby/README.md
@@ -76,7 +76,7 @@
 Then build the Gem:
 
     $ rake gem
-    $ gem install pkg/protobuf-$VERSION.gem
+    $ gem install `ls pkg/google-protobuf-*.gem`
 
 To run the specs: