HADOOP-14909. Fix the word of erasure encoding in the top page. Contributed by Takanobu Asanuma.

(cherry picked from commit 373d0a51955cabff77e934a28ba2de308207374a)

hadoop-project/src/site/markdown/index.md.vm

@@ -34,7 +34,7 @@ Minimum required Java version increased from Java 7 to Java 8
 All Hadoop JARs are now compiled targeting a runtime version of Java 8.
 Users still using Java 7 or below must upgrade to Java 8.
 
-Support for erasure encoding in HDFS
+Support for erasure coding in HDFS
 ------------------
 
 Erasure coding is a method for durably storing data with significant space