Add comment about standardrb usage to README

Author: andyundso

README.md

@@ -439,6 +439,10 @@ $ rake TINYTDS_UNIT_DATASERVER=mydbserver TINYTDS_SCHEMA=sqlserver_2017
 $ rake TINYTDS_UNIT_HOST=mydb.host.net TINYTDS_SCHEMA=sqlserver_azure
 ```
 
+### Code formatting
+
+We are using `standardrb` to format our code. Just run `bundle exec standardrb --fix` to format all Ruby files.
+
 ### Compiling Gems for Windows and Linux
 
 > [!WARNING]