Create an example directory and add some code examples. (#944)

* update example directory

* modify some compile error.

* update with clang-format

* update

* update

* add_definitions("../include/json")

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Wed Jul 10 21:26:16 2019 +0800
#
# On branch code_example
# Your branch is up-to-date with 'origin/code_example'.
#
# Changes to be committed:
#	modified:   example/CMakeLists.txt
#

* change CMakeLists.txt

* update streamWrite.cpp

* update

* Update readFromStream.cpp

* fix typo

example/readFromStream/withComment.json

@@ -0,0 +1,6 @@
+// comment head
+{
+    // comment before
+    "key" : "value"
+    // comment after
+}// comment tail