rand: Update changelog

Author: vks

CHANGELOG.md

@@ -10,7 +10,12 @@ You may also find the [Upgrade Guide](https://rust-random.github.io/book/update.
 
 ## [0.8.5] - unreleased
 ### Fixes
--  Fix build on non-32/64-bit architectures (#1144)
+- Fix build on non-32/64-bit architectures (#1144)
+- Fix "min_const_gen" feature for `no_std` (#1173)
+
+### Rngs
+- `StdRng`: Switch from HC128 to ChaCha12 on emscripten (#1142).
+  We now use ChaCha12 on all platforms.
 
 ## [0.8.4] - 2021-06-15
 ### Additions