Add instructions for taking a state dump (#469)

Author: danfinlay

docs/state_dump.md

@@ -0,0 +1,15 @@
+# How to take a State Dump
+
+Sometimes a UI bug is hard to reproduce, but we'd like to rapidly develop against the application state that caused the bug.
+
+In this case, a MetaMask developer will sometimes ask a user with a bug to perform a "state dump", so we can use some internal tools to reproduce and fix the bug.
+
+To take a state dump, follow these steps:
+
+1. Get the MetaMask popup to the point where it shows the bug (the developer will probably specify exactly where).
+2. Right click on the extension popup UI, and in the menu, click "Inspect". This will open the developer tools.
+3. In case it isn't already selected, click the "Console" tab in the new Developer Tools window.
+4. In the console, type this command exactly: `logState()`. This should print a bunch of JSON text into your console.
+5. Copy that printed JSON text
+6. *Optional*: Annonymize that text if you'd like (you may change all instances of an account address to another valid account address, for example) We may automate the anonymization in the future.
+7. Send that JSON text to the developer, ideally pasting it in the issue regarding the bug.