Adds changelog entry for maxInstances (#2044)

* adds changelog entry for maxInstances * Update CHANGELOG.md Co-Authored-By: Bryan Kendall <bkend@google.com> Co-authored-by: Bryan Kendall <bkend@google.com>

Author: joehan

CHANGELOG.md

@@ -1,4 +1,5 @@
 * Release RTDB Emulator v4.4.1: Bugfix for unreleased feature.
 * Fixes a bug when using `firebase-tools` to delete Firestore documents inside the Functions emulator (#2001).
 * Fixes a bug where `.runtimeconfig.json` files were not properly detected (#1836).
-* Fixes a bug where rules were sometimes read as blank after a file save (#1980).
+* Adds support for setting `maxInstances` on Firebase Functions.
+* Fixes a bug where rules were sometimes read as blank after a file save (#1980).