Move 2FA docs from "Workflow" to "Profile Settings"

cherry-picked

doc/README.md

@@ -7,7 +7,7 @@
 - [Importing to GitLab](workflow/importing/README.md).
 - [Markdown](markdown/markdown.md) GitLab's advanced formatting system.
 - [Permissions](permissions/permissions.md) Learn what each role in a project (guest/reporter/developer/master/owner) can do.
-- [Profile Settings](profile/profile.md)
+- [Profile Settings](profile/README.md)
 - [Project Services](project_services/project_services.md) Integrate a project with external services, such as CI and chat.
 - [Public access](public_access/public_access.md) Learn how you can allow public and internal access to projects.
 - [SSH](ssh/README.md) Setup your ssh keys and deploy keys for secure access to your projects.

doc/profile/profile.md → doc/profile/README.md

 # Profile Settings
 
 - [Preferences](preferences.md)
+- [Two-factor Authentication (2FA)](two_factor_authentication.md)

doc/workflow/README.md

@@ -11,6 +11,5 @@
 - [Project Features](project_features.md)
 - [Project forking workflow](forking_workflow.md)
 - [Protected branches](protected_branches.md)
-- [Two-factor Authentication (2FA)](two_factor_authentication.md)
 - [Web Editor](web_editor.md)
 - ["Work In Progress" Merge Requests](wip_merge_requests.md)