Remove obsolete note about development gems

README.md

@@ -300,18 +300,6 @@ major version.
 
 ## Development
 
-### Bundler tricks for older Rubies
-
-The development gems only work in Ruby 2.3 or later.  When developing
-ftpd for older Rubies, exclude the development gems:
-
-    bundle install --without development
-
-With the current version of bundler (1.13.1), this has the unfortunate
-effect of remembering--forever--that you do not want development gems.
-So before you install gems for Ruby 2.3 or later, remove
-.bundle/config from the project's directory.
-
 ### Tests
 
 To run the cucumber (functional) tests: