JS client: fixed syntax error in npm readme (#1492)

## Description of changes

Incorrect comma, should have been a colon.

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
         - No bug fixes
 - New functionality
	 - No new functionality

## Test plan
*How are these changes tested?*
No functionality changes

## Documentation Changes
*Are all docstrings for user-facing APIs updated if required? Do we need
to make documentation changes in the [docs
repository](https://github.com/chroma-core/docs)?*

Incorrect comma, should have been a colon.

clients/js/README.md

@@ -24,7 +24,7 @@ const collection = await chroma.createCollection({ name: "test-from-js" });
 for (let i = 0; i < 20; i++) {
   await collection.add({
     ids: ["test-id-" + i.toString()],
-    embeddings, [1, 2, 3, 4, 5],
+    embeddings: [1, 2, 3, 4, 5],
     documents: ["test"],
   });
 }