update README (#109)

Author: rohanku

README.md

@@ -4,6 +4,10 @@ An open-source digital implementation of the UCIe 1.1 specification.
 
 You can request a copy of the UCIe 1.1 specification [here](https://www.uciexpress.org/1-1-spec-download).
 
+> [!NOTE]
+> We are currently in the process of rewriting portions of the implementation. Latest changes can be found on the [`dev`](/tree/dev) branch.
+> 
+
 ## Getting Started
 
 Install [sbt](https://www.scala-sbt.org/).