update README.md

Author: atuchin-m

README.md

@@ -52,7 +52,7 @@ By default, `adblock-rust` ships with a built-in domain resolution implementatio
 `adblock-rust` uses uBlock Origin-compatible resources for scriptlet injection and redirect rules.
 The `resource-assembler` feature allows `adblock-rust` to parse these resources directly from the file formats used by the uBlock Origin repository.
 
-#### Thread safety (`unsync-regex-caching`)
+#### Thread safety (`single-thread`)
 
-The `unsync-regex-caching` feature enables optimizations for rule matching speed and the amount of memory used by the engine.
+The `single-thread` feature enables optimizations for rule matching speed and the amount of memory used by the engine.
 This feature can be disabled to make the engine `Send + Sync`, although it is recommended to only access the engine on a single thread to maintain optimal performance.