Update README.md

Author: vsilaev

README.md

@@ -55,7 +55,7 @@ You have to add the following configuration to enable build-time instrumentation
 <source>1.6</source>
 <target>1.6</target>
 <!-- For JDK 21+ uncomment the following compiler settings (instead of source/target) ---> 
-<!-- &dash;&dash;enable-preview is optional, but it allows to use more efficient ScopedValue instead 
+<!-- --enable-preview is optional, but it allows to use more efficient ScopedValue instead 
  of ThreadLocal for continuations core
 <!-- 
 <release>21</release>