feat: update readme

Author: ablaszkiewicz

README.md

@@ -67,7 +67,10 @@ logdash.Info("Hello", "From", "LogDash");
 ### Metrics
 
 ```csharp
+// to set absolute value
 metrics.Set("key", 2);
+
+// or increment / decrement by
 metrics.Mutate("key", 3);
 ```
 
@@ -89,4 +92,4 @@ Contributions are welcome! Feel free to open issues or submit pull requests.
 
 ## Support
 
-If you encounter any issues, please open an issue on GitHub or let us know at [contact@logdash.io](mailto:contact@logdash.io).
+If you encounter any issues, please open an issue on GitHub or let us know at [contact@logdash.io](mailto:contact@logdash.io).