updated docs and tests for backtick codeblocks

source/docs/plugins/github-style-codeblock/index.markdown

@@ -10,6 +10,8 @@ With the `backtick_codeblock` filter you can use Github's lovely back tick synta
 Simply start a line with three back ticks followed by a space and the language you're using. Tab in four spaces
 for your code snippets, and then finish your code block with three more back ticks.
 
+**Note: Back tick code blocks are only supported in HTML and Markdown. With the Textile markup language, use the [codeblocks](/docs/plugins/codeblock/) instead.**
+
 #### Syntax
 
 {% codeblock %}

source/test/code/markdown/index.markdown

@@ -0,0 +1,19 @@
+---
+layout: page
+title: "Code"
+date: 2011-07-30 08:45
+footer: false
+sidebar: false
+---
+
+``` coffeescript
+    Tweets = 1
+
+    module.exports = Tweets
+```
+
+``` coffeescript
+    Tweets = 1
+    foo && bar
+    module.exports = Tweets
+```

source/test/code/textile/index.textile

@@ -0,0 +1,20 @@
+---
+layout: page
+title: "Textile"
+date: 2011-08-01 08:13
+comments: true
+sharing: true
+footer: true
+---
+
+``` coffeescript
+    _Tweets_ = 1
+
+    module.exports = Tweets
+```
+
+``` coffeescript
+    Tweets = 1
+    foo && bar
+    module.exports = Tweets
+```