Update README.md - An initial version

Author: youhanaNaseim

README.md

@@ -1,4 +1,15 @@
-This SDK is under development.
+### **This SDK is still under development & not ready for adoption yet.**
+
+# Antithesis Rust SDK
+
+This library provides methods for Rust programs to configure the [Antithesis](https://antithesis.com) platform. It contains three kinds of functionality:
+* Assertion macros that allow you to define test properties about your software or workload.
+* Randomness functions for requesting both structured and unstructured randomness from the Antithesis platform.
+* Lifecycle functions that inform the Antithesis environment that particular test phases or milestones have been reached.
+
+For general usage guidance see the [Antithesis Rust SDK Documentation](https://antithesis.com/docs/using_antithesis/sdk/rust_sdk.html)
+
+### Notes
 
 When using llvm's link/loader from clang prior to version 16, it may be necessary to explicitly request 
 that unused sections are NOT removed from the resulting binary.