README.md in mortar-0.15.47 vs README.md in mortar-0.15.48

- old
+ new
@@ -14,18 +14,22 @@
 * [Ruby](http://www.ruby-lang.org/en/downloads/) 1.8.7 or later
 * [Gem](https://rubygems.org/pages/download) (included with Ruby 1.9.2+)
 
 ## Installation
 
-    gem install mortar
+    sudo gem install mortar --bindir /usr/local/bin
 
 # Development
 
 To develop on the gem, install the bundle, and then use bundle exec to run mortar:
 
     gem install bundler
     bundle install
     bundle exec mortar <command> <args>
+
+If you want to run the modified `mortar` from a different directory (e.g. from `dd-analytics`), you need to do it like this:
+
+    BUNDLE_GEMFILE="/path/to/mortar/Gemfile" bundle exec mortar
 
 # Tests
 
 You can run all the RSpec tests with rake:
 