Tweak nested JSON docs

docs/README.md

@@ -681,7 +681,40 @@ Other JSON types, however, are not allowed with `--form` or `--multipart`.
         "about": {
             "mission": "Make APIs simple and intuitive",
             "homepage": "httpie.io",
-    }
+            "stars": 54000
+        },
+        "apps": [
+            "Terminal",
+            "Desktop",
+            "Web",
+            "Mobile"
+        ]
+    }
+}
+```
+
+#### Introduction
+
+Let’s start with a simple example, and build a simple search query:
+
+```bash
+$ http --offline --print=B pie.dev/post \
+  category=tools \
+  search[type]=id \
+  search[id]:=1
+```
+
+In the example above, the `search[type]` is an instruction for creating an object called `search`, and setting the `type` field of it to the given value (`"id"`).
+
+Also note that, just as the regular syntax, you can use the `:=` operator to directly pass raw JSON values (e.g, numbers in the case above).
+
+```json
+{
+    "category": "tools",
+    "search": {
+        "id": 1,
+        "type": "id"
+    }
 }
 ```