Add documentation example ex2.

docs/examples/ex2/example-2.yang

+module example-2 {
+
+  yang-version "1.1";
+
+  namespace "http://example.com/example-2";
+
+  prefix "ex2";
+
+  container top {
+    leaf-list foo {
+      type uint8;
+    }
+    leaf bar {
+      type boolean;
+    }
+  }
+}

docs/examples/ex2/example-2.yin

+<?xml version="1.0" encoding="utf-8"?>
+<module name="example-2"
+        xmlns="urn:ietf:params:xml:ns:yang:yin:1"
+        xmlns:ex2="http://example.com/example-2">
+  <yang-version value="1.1"/>
+  <namespace uri="http://example.com/example-2"/>
+  <prefix value="ex2"/>
+  <container name="top">
+    <leaf-list name="foo">
+      <type name="uint8"/>
+    </leaf-list>
+    <leaf name="bar">
+      <type name="boolean"/>
+    </leaf>
+  </container>
+</module>

docs/examples/ex2/example-data.json

+{
+  "example-2:top": {
+    "foo": [
+      1,
+      2
+    ],
+    "bar": true
+  }
+}

docs/examples/ex2/example-data.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+  <top xmlns="http://example.com/example-2">
+    <foo>1</foo>
+    <foo>2</foo>
+    <bar>true</bar>
+  </top>
+</data>

docs/examples/ex2/hello.xml

+<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+<capabilities>
+<capability>urn:ietf:params:netconf:base:1.1</capability>
+<capability>http://example.com/example-2?module=example-2&amp;features=</capability>
+</capabilities>
+</hello>

docs/examples/ex2/yang-library-ex2.json

+{
+  "ietf-yang-library:modules-state": {
+    "module-set-id": "XXXX",
+    "module": [
+      {
+        "name": "example-2",
+        "namespace": "http://example.com/example-2",
+        "revision": "",
+        "conformance-type": "implement"
+      }
+    ]
+  }
+}