Remove references to java.util.Date (scala#3029)

Author: bwignall

_overviews/core/implicit-classes.md

@@ -77,7 +77,7 @@ Implicit classes have the following restrictions:
 **2. They may only take one non-implicit argument in their constructor.**
 
 
-    implicit class RichDate(date: java.util.Date) // OK!
+    implicit class RichDate(date: java.time.LocalDate) // OK!
     implicit class Indexer[T](collection: Seq[T], index: Int) // BAD!
     implicit class Indexer[T](collection: Seq[T])(implicit index: Index) // OK!
 

_style/scaladoc.md

@@ -208,7 +208,7 @@ sure to indicate the actual method names:
        *  @return a new Person instance with the age determined by the
        *          birthdate and current date.
        */
-      def apply(name: String, birthDate: java.util.Date) = {}
+      def apply(name: String, birthDate: java.time.LocalDate) = {}
     }
 
 If your object holds implicit conversions, provide an example in the

_zh-cn/overviews/core/implicit-classes.md

@@ -61,7 +61,7 @@ Scala 2.10引入了一种叫做隐式类的新特性。隐式类指的是用impl
 
 2. 构造函数只能携带一个非隐式参数。
 ````
-    implicit class RichDate(date: java.util.Date) // 正确！
+    implicit class RichDate(date: java.time.LocalDate) // 正确！
     implicit class Indexer[T](collecton: Seq[T], index: Int) // 错误！
     implicit class Indexer[T](collecton: Seq[T])(implicit index: Index) // 正确！
 ````