Prepare changelog for v19.6.0-rc.1

CHANGELOG.md

@@ -1,3 +1,15 @@
+Changes in [19.6.0-rc.1](https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.6.0-rc.1) (2022-09-20)
+============================================================================================================
+
+## ✨ Features
+ * Add a property aggregating all names of a NamespacedValue ([\#2656](https://github.com/matrix-org/matrix-js-sdk/pull/2656)).
+ * Implementation of MSC3824 to add action= param on SSO login ([\#2398](https://github.com/matrix-org/matrix-js-sdk/pull/2398)). Contributed by @hughns.
+ * Add invited_count and joined_count to sliding sync room responses. ([\#2628](https://github.com/matrix-org/matrix-js-sdk/pull/2628)).
+ * Base support for MSC3847: Ignore invites with policy rooms ([\#2626](https://github.com/matrix-org/matrix-js-sdk/pull/2626)). Contributed by @Yoric.
+
+## 🐛 Bug Fixes
+ * Fix handling of remote echoes doubling up ([\#2639](https://github.com/matrix-org/matrix-js-sdk/pull/2639)). Fixes #2618.
+
 Changes in [19.5.0](https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.5.0) (2022-09-13)
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