Add additional recommendations for using the profile.js script.

Author: jamestalmage

maintaining.md

@@ -27,10 +27,25 @@
 
 ## Profiling
 
+You should first install `iron-node` and / or `devtool` globally:
+
+```
+$ npm install --global iron-node
+$ npm install --global devtool
+```
+
 In the root of a project using AVA, run:
 
 ```
 $ iron-node node_modules/ava/profile.js <test-file>
+# or
+$ devtool node_modules/ava/profile.js <test-file>
 ```
 
-After `iron-node` has loaded, activate the Dev Tools profiling, and then hit <kbd>Cmd</kbd> <kbd>R</kbd> to rerun the tests.
+Once the Dev Tools window has loaded, activate Memory or CPU profiling, and then hit <kbd>Cmd</kbd> <kbd>R</kbd> to rerun the tests.
+
+As soon as the tests finish, stop the recording and inspect the profiler results.
+
+A good introduction to CPU and Memory profiling can be found [here](https://www.youtube.com/watch?v=KKwmdTByxLk)
+
+You may also want to check out the Settings page in Dev Tools and enable one or more options in the Profiling section.