readme: note about optimized for querying

Author: assafmo

README.md

@@ -23,6 +23,8 @@ Usage of SQLiteQueryServer:
         SQL query to prepare for
 ```
 
+Note: SQLiteQueryServer is optimized for the SELECT command. Other commands such as INSERT, UPDATE, DELETE, CREATE, etc might be slow because SQLiteQueryServer doesn't use transactions (yet). Also, the response format and error messages from these commands can be odd or unexpected.
+
 # Examples
 
 ## Creating a server