Update readme

README.md

@@ -108,8 +108,13 @@ Chronograph.configure(TableTheme.SIMPLE);
 
 
 ## Limitations
+
+### Time resolution
 This project is utilizing `System.nanoTime()` which has some inherent issues with very quick task times. It does have a nanosecond resolution, but not a nanosecond precision. These are still usually orders of magnitude away from what you are trying to measure, so it is not a problem. If you are micro-benchmarking, consider using a framework like [JMH](https://mvnrepository.com/artifact/org.openjdk.jmh/jmh-core).
 
 If you would like to know more:
   * [https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/System.html#nanoTime()](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/System.html#nanoTime())
   * [https://shipilev.net/blog/2014/nanotrusting-nanotime/#_timers](https://shipilev.net/blog/2014/nanotrusting-nanotime/#_timers)
+
+### Thread safety
+The Chronograph is NOT thread safe.