Fix #667: Update header grammar on How-to page

- Changed section title from "How to's" to "How-tos".
- Updated subhead to add the missing "and" between "documents" and "meetings" and removed the comma.

Author: virginie-sankara

src/main/en/how-tos/index.njk

@@ -1,6 +1,6 @@
 ---
-title: How to’s
-description: Tips and core steps to help make all your digital products and content, such as documents, meetings, accessible.
+title: How-tos
+description: Tips and core steps to help make all your digital products and content, such as documents and meetings, accessible.
 toggle: comment-faire
 tags:
   - main