feat: Add sync_library_updates url in help tokens (#38438)

Adds a new URL `sync_library_updates` to the `help_tokens`

Author: ChrisChV

cms/envs/help_tokens.ini

@@ -27,6 +27,7 @@ video = course_author:references/course_development/guide_to_video.html
 certificates = course_author:concepts/open_edx_platform/about_certificates.html
 content_highlights = course_author:how-tos/course_development/manage_course_highlight_emails.html
 social_sharing = course_author:how-tos/course_development/social_sharing.html
+sync_library_updates = course_author:how-tos/course_development/sync_a_library_update_to_your_course.html
 
 # below are the language directory names for the different locales
 [locales]