Merge branch 'change-markdown-help-location' into 'master'

Fix location of markdown help

Resolves #21208, and incorrect link to the markdown style guide

See merge request !5945

app/views/projects/notes/_hints.html.haml

@@ -2,7 +2,7 @@
 .comment-toolbar.clearfix
   .toolbar-text
     Styling with
-    = link_to 'Markdown', help_page_path('markdown/markdown'), target: '_blank', tabindex: -1
+    = link_to 'Markdown', help_page_path('user/markdown'), target: '_blank', tabindex: -1
     - if supports_slash_commands
       and
       = link_to 'slash commands', help_page_path('user/project/slash_commands'), target: '_blank', tabindex: -1