fix ExerciseSelector props

Author: jrakibi

decoding/bitcoin-opcodes.mdx

@@ -61,7 +61,6 @@ Test your implementation by:
 3. Observing the result on the stack and the feedback message.
 
 <ExerciseSelector
-  exerciseTitle="OP_ADD Implementation Exercise"
   sandpackConfig={{
     options: {
       showLineNumbers: true,