Add deprecation message to README

Author: Borewit

README.md

@@ -8,6 +8,10 @@
 
 # peek-readable
 
+> [!WARNING]  
+> **This modules is deprecated.**
+> I merged its functionality into [strtok3](https://github.com/Borewit/strtok3/pull/1234), under the assumption it is solely used as a dependency [strtok3](https://github.com/Borewit/strtok3).  
+
 A promise based asynchronous stream reader, which makes reading from a stream easy.
 
 Allows to read and peek from a [Readable Stream](https://nodejs.org/api/stream.html#stream_readable_streams)