add patch_inplace function (#3581)

* add patch_inplace function to json class

* add documentation

* fix up docs

docs/examples/patch_inplace.output

@@ -0,0 +1,13 @@
+Before
+{
+    "baz": "qux",
+    "foo": "bar"
+}
+
+After
+{
+    "baz": "boo",
+    "hello": [
+        "world"
+    ]
+}