Add notifications documentation.

doc/workflow/README.md

@@ -4,3 +4,4 @@
 - [Groups](groups.md)
 - [Labels](labels.md)
 - [GitLab Flow](gitlab_flow.md)
+- [Notifications](notifications.md)

doc/workflow/notifications.md

+# GitLab Notifications
+
+GitLab has a notifications system in place to notify a user of events important for the workflow.
+
+## Notification settings
+
+Under user profile page you can find the notification settings.
+
+![notification settings](notifications/settings.png)
+
+We can divide the notification settings into three groups:
+
+* Global Settings
+* Group Settings
+* Project Settings
+
+Each of these settings have levels of notification:
+
+* Disabled - turns off notifications
+* Participating - receive notifications from related resources
+* Watch - receive notifications from projects or groups user is a member of
+* Global - notifications as set at the global settings
+
+#### Global Settings
+
+Global Settings are at the bottom of the hierarchy.
+
+Any setting set here will be overriden by a setting at the group or a project level.
+Group or Project setting can use `global` notification setting which will then use
+anything that is set at Global Settings.
+
+#### Group Settings
+
+Group Settings are taking presedence to Global Settings but are on a level below Project Settings.
+This means that you can set a different level of notifications per group while still being able
+to have a finer level setting per project.
+Organization like this is suitable for users that belong to different groups but don't have the
+same need for being notified for every group they are member of.
+
+#### Project Settings
+
+Project Settings are at the top level and any setting placed at this level will take presedence of any
+other setting.
+This is suitable for users that have different needs for notifications per project basis.
+
+## Notification events
+
+Below is the table of events users can be notified of:
+
+| Event                        | Sent to                                                           | Settings level               |
+|------------------------------|-------------------------------------------------------------------|------------------------------|
+| New SSH key added            | User                                                              | Security email, always sent. |
+| New email added              | User                                                              | Security email, always sent. |
+| New user created             | User                                                              | Sent on user creation, except for omniauth (LDAP)|
+| New issue created            | Issue assignee [1], project members [2]                           | [1] not disabled, [2] higher than participating |
+| User added to project        | User                                                              | Sent when user is added to project |
+| Project access level changed | User                                                              | Sent when user project access level is changed |
+| User added to group          | User                                                              | Sent when user is added to group |
+| Project moved                | Project members [1]                                               | [1] not disabled |
+| Group access level changed   | User                                                              | Sent when user group access level is changed |
+| Close issue                  | Issue author [1], issue assignee [2], project members [3]         | [1] [2] not disabled, [3] higher than participating |
+| Reassign issue               | New issue assignee [1], old issue assignee [2]                    | [1] [2] not disabled |
+| Reopen issue                 | Project members [1]                                               | [1] higher than participating |
+| New merge request            | MR assignee [1]                                                   | [1] not disabled |
+| Reassign merge request       | New MR assignee [1], old MR assignee [2]                          | [1] [2] not disabled |
+| Close merge request          | MR author [1], MR assignee [2], project members [3]               | [1] [2] not disabled, [3] higher than participating |
+| Reopen merge request         | Project members [1]                                               | [1] higher than participating |
+| Merge merge request          | MR author [1], MR assignee [2], project members [3]               | [1] [2] not disabled, [3] higher than participating |
+| New comment                  | Mentioned users [1], users participating [2], project members [3] | [1] [2] not disabled, [3] higher than participating |
+
+