Typo Correction (#3621)

Code (in this context) is mass noun, and thus has no plural form.
Co-authored-by: NMichael Wyatt <michaelwyatt@microsoft.com>

docs/_pages/training.md

@@ -44,7 +44,7 @@ optimizations on advanced hyperparameter tuning and optimizers. For example:
   | 64 V100 GPUs   | DeepSpeed |            **8.68** hr|
   | 16 V100 GPUs   | DeepSpeed |           **33.22** hr|
 
-  *BERT codes and tutorials will be available soon.*
+  *BERT code and tutorials will be available soon.*
 
 * DeepSpeed trains GPT2 (1.5 billion parameters) 3.75x faster than state-of-art, NVIDIA
   Megatron on Azure GPUs.