Repo move announcement

PiperOrigin-RevId: 921705653

Author: dmitriplotnikov

README.md

@@ -1,5 +1,12 @@
 # C++ Implementations of the Common Expression Language
 
+> [!WARNING]
+> **On June 16, 2026, this repository will move to
+> github.com/cel-expr/cel-cpp!**
+>
+> Please update your links and dependencies. See the [pinned
+> issue](https://github.com/google/cel-cpp/issues/2029) for details.
+
 For background on the Common Expression Language see the [cel-spec][1] repo.
 
 This is a C++ implementation of a [Common Expression Language][1] runtime,