Update archive notice. (#3507)

Author: mgreisen

README.md

@@ -1,6 +1,8 @@
 # <img src="docs/onefuzz_text.svg" height="120" alt="OneFuzz" />
 
-# IMPORTANT NOTICE
+# :exclamation: IMPORTANT NOTICE :exclamation:
+
+**_August 31, 2023_**.
 
 **_Since September 2020 when OneFuzz was first open sourced, we’ve been on a journey to create a best-in-class orchestrator for running fuzzers, driving security and quality into our products._**
 
@@ -13,6 +15,10 @@
 
 **_The OneFuzz team._**
 
+---
+**_Update: September 15 2023:_**
+**_Our current target to archive the project is September 30th, 2023._**
+
 ---
 
 [![Onefuzz build status](https://github.com/microsoft/onefuzz/workflows/Build/badge.svg?branch=main)](https://github.com/microsoft/onefuzz/actions/workflows/ci.yml?query=branch%3Amain)