add info to readme about the change

Author: hoeck

README.md

@@ -1,5 +1,7 @@
 # 📊 Benchmark Comparison of Packages with Runtime Validation and TypeScript Support
 
+** ⚡⚠ Benchmark results have changed after switching to isolated node processes for each benchmarked package, see [#864](https://github.com/moltar/typescript-runtime-type-benchmarks/issues/864) ⚠⚡ **
+
 ## Benchmark Results
 
 [![Fastest Packages - click to view details](docs/results/preview.svg)](https://moltar.github.io/typescript-runtime-type-benchmarks)