Update toc.yml

Made title sentence case.

Author: Court72

articles/machine-learning/toc.yml

@@ -388,7 +388,7 @@
     - name: Debug & troubleshoot parallel run step
       displayName: debug_batch consume pipeline parallelrunstep inference
       href: how-to-debug-parallel-run-step.md
-    - name: Iterating and Evolving Machine Learning Pipelines
+    - name: Iterating and evolving machine learning pipelines
       displayName: modularizing testing
       href: concept-pipeline-practices-tips.md
   - name: Manage resource quotas