Merging changes synced from https://github.com/MicrosoftDocs/visualstudio-docs-pr (branch live)

Author: ghogen

docs/toc.yml

@@ -352,6 +352,8 @@
         - name: Overview
           displayName: refactoring
           href: ide/refactoring-in-visual-studio.md
+        - name: Add null checks for all parameters
+          href: ide\reference\add-null-checks-for-parameters.md
         - name: Change method signature
           href: ide/reference/change-method-signature.md
         - name: Convert anonymous type to class