Remove "overview" in Javadoc

Author: dmikurube

README.md

@@ -1,12 +1,10 @@
-Embulk Utilities for Ruby Time
-===============================
-
-Almost Ruby-compatible date-time processor for Embulk and Embulk plugins.
+Almost Ruby-compatible date-time processor for Embulk and Embulk plugins
+=========================================================================
 
 For Embulk plugin developers
 -----------------------------
 
-* [Javadoc](https://dev.embulk.org/embulk-util-config/)
+* [Javadoc](https://dev.embulk.org/embulk-util-rubytime/)
 
 For Maintainers
 ----------------

build.gradle

@@ -134,7 +134,6 @@ javadoc {
     options {
         locale = "en_US"
         encoding = "UTF-8"
-        overview = "src/main/html/overview.html"
         links "https://docs.oracle.com/javase/8/docs/api/"
     }
 }