Update README documentation timestamp

Author: hokagedami

README.md

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 A Serilog enricher that adds call stack information to log events in an exception-like format. This enricher helps with debugging and tracing by providing detailed context about where log events originated, displaying the call stack in an intuitive format similar to exception stack traces.
 
+_Last updated: August 2025_
+
 ## Features
 
 - **Exception-like Format**: Display call stack in familiar format: `Method:Line --> Method:Line --> Method:Line`