Fix typos in index.md

Author: tison <[email protected]>

Reviewers: [email protected]

Closes apache#812 from TisonKun/document_2

Author: tisonkun

zookeeper-docs/src/main/resources/markdown/index.md

@@ -30,15 +30,15 @@ ask the [mailing list](http://zookeeper.apache.org/mailing_lists.html) or browse
 archives.
 
 + **ZooKeeper Overview**
-    Technical Overview Documents for Client Developers, Adminstrators, and Contributors
+    Technical Overview Documents for Client Developers, Administrators, and Contributors
     + [Overview](zookeeperOver.html) - a bird's eye view of ZooKeeper, including design concepts and architecture
     + [Getting Started](zookeeperStarted.html) - a tutorial-style guide for developers to install, run, and program to ZooKeeper
     + [Release Notes](releasenotes.html) - new developer and user facing features, improvements, and incompatibilities
 + **Developers**
     Documents for Developers using the ZooKeeper Client API
     + [API Docs](api/index.html) - the technical reference to ZooKeeper Client APIs
     + [Programmer's Guide](zookeeperProgrammers.html) - a client application developer's guide to ZooKeeper
-    + [ZooKeeper Java Example](javaExample.html) - a simple Zookeeper client appplication, written in Java
+    + [ZooKeeper Java Example](javaExample.html) - a simple Zookeeper client application, written in Java
     + [Barrier and Queue Tutorial](zookeeperTutorial.html) - sample implementations of barriers and queues
     + [ZooKeeper Recipes](recipes.html) - higher level solutions to common problems in distributed applications
 + **Administrators & Operators**