Update preperable-interface.md

There is a typo in the title
diff --git a/source/getting-started/preperable-interface.md b/source/getting-started/preperable-interface.md
index 2755c79..1cf9918 100644
--- a/source/getting-started/preperable-interface.md
+++ b/source/getting-started/preperable-interface.md
@@ -1,6 +1,6 @@
 ---
 layout: default
-title: Preperable Interface
+title: Preparable Interface
 parent:
     title: Getting started
     url: index.html