Regulate top-level arrays (#1292)

* Redesign the starting path

* Do not cast `:=[1,2,3]` to a top-level array

docs/README.md

@@ -854,6 +854,47 @@ $ http PUT pie.dev/put \
 You can also apply the nesting to the items by referencing their index:
 
 ```bash
+http --offline --print=B pie.dev/post \
+    [0][type]=platform [0][name]=terminal \
+    [1][type]=platform [1][name]=desktop
+```
+
+```json
+[
+    {
+        "type": "platform",
+        "name": "terminal"
+    },
+    {
+        "type": "platform",
+        "name": "desktop"
+    }
+]
+```
+
+##### Escaping behavior
+
+Nested JSON syntax uses the same [escaping rules](#escaping-rules) as
+the terminal. There are 3 special characters, and 1 special token that you can escape.
+
+If you want to send a bracket as is, escape it with a backslash (`\`):
+
+```bash
+$ http --offline --print=B pie.dev/post \
+  'foo\[bar\]:=1' \
+  'baz[\[]:=2' \
+  'baz[\]]:=3'
+```
+
+```json
+{
+    "baz": {
+        "[": 2,
+        "]": 3
+    },
+    "foo[bar]": 1
+}
+```
 
 If you want to send the literal backslash character (`\`), escape it with another backslash: