Readme fix

Author: octavonce

README.md

@@ -13,7 +13,7 @@ static GLOBAL: MiMalloc = MiMalloc;
 ```
 
 ## Usage without secure mode
-By default this library builds mimalloc in safe-mode. This means that
+By default this library builds mimalloc in secure mode. This means that
 heap allocations are encrypted, but this results in a 3% increase in overhead.
 
 To disable secure mode, in `Cargo.toml`: