changelog: List UART mux support and iniparser dependency

UART mux support is a notable feature. Make sure users can be aware
of it.

Change-Id: I26ae052f5b64d4eaaea1f814bfddf9632739f2c7
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f38aeb..b8cc49a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,13 @@
 
 1. config: Added support for the `aspeed-uart-routing` configuration key
 2. config: Added support for the `ringbuffer-size` configuration key
+3. UART multiplexer support
+
+   More details can be found [in the documentation](docs/mux-support.md).
+
+### Changed:
+
+1. The bespoke config parser was replaced with iniparser
 
 ### Removed