Fix number of iterations in example code (#2240)

Co-authored-by: Svetlana Karslioglu <svekars@fb.com>

Author: felixdivo

beginner_source/flava_finetuning_tutorial.py

@@ -172,7 +172,7 @@ def transform(tokenizer, input):
     loss.backward()
     optimizer.step()
     print(f"Loss at step {idx} = {loss}")
-    if idx > MAX_STEPS-1:
+    if idx >= MAX_STEPS-1:
       break