Update CHANGELOG.md

CHANGELOG.md

@@ -13,6 +13,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Assign patterns to variables (e.g. `let x::(t = y::_) = [1, 2, 3, 4]` where `t == [2, 3, 4]`)
 - Add builtin types (`AENS.name, AENS.pointee, Chain.ttl, Chain.base_tx, Chain.ga_meta_tx, Chain.paying_for_tx`) to
   the calldata and result decoder
+- Patterns guards
+  ```
+  switch(x)
+    a::[] | a > 10 => 1
+    _              => 2
+  ```
+  ```
+  function
+    f(a::[]) | a > 10 = 1
+    f(_)              = 2
+  ```
 ### Changed
 - Fixed the ACI renderer, it shouldn't drop the `stateful` modifier
 ### Removed