Updated TOC to align with rest of Docs

Author: ntrogh

articles/load-testing/toc.yml

@@ -28,7 +28,7 @@
   items: 
     - name: Key concepts
       href: concept-load-testing-concepts.md
-- name: How-tos
+- name: How-to guides
   expanded: true
   items: 
     - name: Compare test runs