Update docs and add susy-version function

Author: mirisuzanne

.sassdoc/su-math.html

@@ -1,5 +1,5 @@
 theme: Herman
-dest: .sassdoc
+dest: docs/
 
 display:
   access: public
@@ -15,6 +15,7 @@ groups:
   x-normal: '[Susy Normalization]'
   x-parser: '[Susy Syntax Parser]'
   x-validation: '[Su Input Validation]'
+  x-version: '[Release Notes]'
 
 herman:
   sass:

.sassdoc/x-normal.html

@@ -1,6 +1,12 @@
 Changelog
 =========
 
+3.0.1 - August 27, 2017
+-----------------------
+
+- NEW: `susy-version()` function for accessing the active version number.
+- Minor documentation improvements.
+
 
 3.0.0 - June 29, 2017
 ---------------------