Add CSON primer

book/02-using-atom/sections/02-text.asc

@@ -289,6 +289,8 @@ console.log("crash");
 
 The string `"crash"` would be initially selected and pressing tab again would place the cursor after the `;`
 
+WARNING: Snippet keys, unlike CSS selectors, can only be repeated once per level. If there are duplicate keys at the same level, then only the last one will be read. See <<_cson,Configuring with CSON>> for more information.
+
 ===== Multi-line Snippet Body
 
 You can also use multi-line syntax using `"""` for larger templates:

book/02-using-atom/sections/06-customizing.asc

@@ -3,6 +3,55 @@
 
 Now that we are feeling comfortable with just about everything built into Atom, let's look at how to tweak it. Perhaps there is a keybinding that you use a lot but feels wrong or a color that isn't quite right for you. Atom is amazingly flexible, so let's go over some of the simpler flexes it can do.
 
+[[_cson]]
+==== Configuring with CSON
+All of Atom's config files (with the exception of your <<_style_tweaks, style sheet>> and your <<_the_init_file, Init Script>>) are written in CSON, short for CoffeeScript Object Notation.footnoteref:[cson, https://github.com/bevry/cson#what-is-cson] Just like its namesake JSON (JavaScript Object Notation)footnoteref:[json, http://json.org/], CSON is a text format for storing structured data in the form of simple objects made up of key-value pairs.
+
+----
+key:
+  key: value
+  key: value
+  key: [value, value]
+----
+
+Objects are the backbone of any CSON file, and are delineated with either indentation (as in the above example), or with curly brackets (`{}`). A key's value can either be a String, a Number, an Object, a Boolean, `null`, or an Array of any of these data types.
+
+WARNING: Unlike CSS's selectors, CSON's keys can only be repeated once per object. If there are duplicate keys, then the last usage of that key overwrites all others, as if they weren't there. The same holds true for Atom's config files.
+
+[WARNING]
+====
+Avoid this:
+
+[source,coffee]
+----
+# DON'T DO THIS
+'.source.js':
+  'console.log':
+    'prefix': 'log'
+    'body': 'console.log(${1:"crash"});$2'
+
+# Only this snippet will be loaded
+'.source.js':
+  'console.error':
+    'prefix': 'error'
+    'body': 'console.error(${1:"crash"});$2'
+----
+
+Use this instead:
+
+[source,coffee]
+----
+# DO THIS: Both of these will be loaded
+'.source.js':
+  'console.log':
+    'prefix': 'log'
+    'body': 'console.log(${1:"crash"});$2'
+  'console.error':
+    'prefix': 'error'
+    'body': 'console.error(${1:"crash"});$2'
+----
+====
+
 [[_style_tweaks]]
 ==== Style Tweaks