Add note about new Literal codes

Bug: https://github.com/dart-lang/sdk/issues/34259
Change-Id: I0efd1c750f453b76e7e91482abc5843196c5b8ad
Reviewed-on: https://dart-review.googlesource.com/c/88761
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd8d5e4..1134e55 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,9 @@
 
     *   `INVALID_LITERAL_ANNOTATION` when something other than a const
         constructor is annotated with `@literal`.
+    *   `NON_CONST_CALL_TO_LITERAL_CONSTRUCTOR` and
+        `NON_CONST_CALL_TO_LITERAL_CONSTRUCTOR_USING_NEW` when a `@literal`
+        const constructor is called in a non-const context (or with `new`).
     *   `SUBTYPE_OF_SEALED_CLASS` when any class or mixin subclasses (extends,
         implements, mixes in, or constrains to) a `@sealed` class, and the two
         are declared in different packages.