Fixing bad filename in changelog

Author: weaverryan

CHANGELOG.md

@@ -36,7 +36,7 @@ for a full description of all of the valid browser descriptions.
  * Introduced a new `configureSplitChunks()` method that can be
    used to further configure the `optimizations.splitChunks` configuration.
 
- * A new `entrypoints.js` file is now always output. For expert
+ * A new `entrypoints.json` file is now always output. For expert
    use-cases, the `optimizations.splitChunks.chunks` configuration
    can be set via `configureSplitChunks()` to `all`. Then, you
    can write some custom server-side code to parse the `entrypoints.js`