Clarify that  json is being encoded in lexicographical order.

PiperOrigin-RevId: 746566416
Change-Id: I77de59d22c6666fd1bde986f0e80fd0715ba71b5
diff --git a/src/main/java/net/starlark/java/lib/json/Json.java b/src/main/java/net/starlark/java/lib/json/Json.java
index 3a4321d..716f33dee 100644
--- a/src/main/java/net/starlark/java/lib/json/Json.java
+++ b/src/main/java/net/starlark/java/lib/json/Json.java
@@ -96,8 +96,8 @@
               + " floating-point value.\n"
               + "<li>A string value is encoded as a JSON string literal that denotes the value. "
               + " Each unpaired surrogate is replaced by U+FFFD.\n"
-              + "<li>A dict is encoded as a JSON object, in key order.  It is an error if any key"
-              + " is not a string.\n"
+              + "<li>A dict is encoded as a JSON object, in lexicographical key order.  It is an"
+              + " error if any key is not a string.\n"
               + "<li>A list or tuple is encoded as a JSON array.\n"
               + "<li>A struct-like value is encoded as a JSON object, in field name order.\n"
               + "</ul>\n"