README.md in snmp-open-0.1.5 vs README.md in snmp-open-0.2.0

@@ -34,9 +34,11 @@
 end
 ```
 
 Naturally, configuration can also be supplied through `snmp.conf(5)`.
 
+Environment variables can be given using the `env` keyword parameter to `SNMP::Open.new`. For example, the `SNMP_PERSISTENT_FILE` and `SNMPCONFPATH` variables are understood by Net-SNMP commands and indicate paths in which to look for configuration files.
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).