doc(llnode): add user journey guide

documentation/crash/step2/using_llnode.md

@@ -1 +1,57 @@
-// TODO
+# Using `llnode` for post-mortem debugging
+
+You probably already experienced crashes that only happen in production.
+You'd like to reproduce it and step through instructions, 
+but it will imply stopping your Node.js process and certainly 
+degrade the user experience.
+
+The purpose of this guide is to help you to find route causes
+of your application crashes in production.
+
+Before jumping into the code, let's clarify a few core concepts
+that will helps you to go thoroughly through this tutorial.
+
+## Concepts
+
+> ✋ If you familliar with the concept of core dump and `lldb`, 
+> please skip this chapter, and start [here](#explore-your-firstcore-dump)
+
+### What is a core dump?
+### What is `lldb`?
+
+## Explore your first core dump
+
+### Setup
+
+Open your favorite editor and copy-paste this piece of code.
+
+```js
+// script.js
+
+const log = {
+  info: (message) => console.log("Info: " + message),
+  error: (message) => console.log("Error: " + message)
+}
+
+log.debug("This should crash");
+```
+
+### Create a code dump
+### Use lldb
+### Something is missing in the frames
+
+## Reveal invisible frames with `llnode`
+
+This is not ideal for dealing with these blank lines.
+Let's see how `llnode` can help us.
+
+### Install `llnode` plugin
+### Explore missing traces (`v8 bt`)
+
+## Beyond the backtrace
+
+Revealing Javascript frames is not the only capacity of `llnode`.
+
+### Inspect framces (`v8 i`)
+### Explore objects (`v8 findjsobjects` / `v8 findjsinstances`)
+### Find object references (`v8 findrefs`)