add link to compat docs in readme

Author: nrednav

README.md

@@ -63,6 +63,9 @@ This section explains how to setup the project locally for development.
 ### Dependencies
 
 - Elixir `~> 1.12` (OTP 24+)
+  - See [Compatibility and
+    deprecations](https://hexdocs.pm/elixir/1.18.4/compatibility-and-deprecations.html)
+    for more information
 
 ### Get the Source