Merge pull request #1689 from g199209/master

Add CMake minimum version required.
diff --git a/RapidJSONConfig.cmake.in b/RapidJSONConfig.cmake.in
index 8c5ca5f..c25d312 100644
--- a/RapidJSONConfig.cmake.in
+++ b/RapidJSONConfig.cmake.in
@@ -1,4 +1,8 @@
 ################################################################################
+# CMake minimum version required
+cmake_minimum_required(VERSION 3.0)
+
+################################################################################
 # RapidJSON source dir
 set( RapidJSON_SOURCE_DIR "@CONFIG_SOURCE_DIR@")