Fix scikit-image documentation

lib/docs/scrapers/scikit_image.rb

@@ -4,7 +4,7 @@ module Docs
     self.slug = 'scikit_image'
     self.type = 'sphinx'
     self.release = '0.13.0'
-    self.base_url = 'http://scikit-image.org/docs/0.12.x/'
+    self.base_url = 'http://scikit-image.org/docs/0.13.x/'
     self.links = {
       home: 'http://scikit-image.org/',
       code: 'https://github.com/scikit-image/scikit-image'