Add information about account section

docs/user/01_personal_account.rst

+Managing your personal account
+------------------------------
+
+Each logged in user has several options to provided through the AlekSIS
+core. Which of these items are display depends on whether the user has a
+person and what your system administrator has configured.
+
+.. _sec:Notifications:
+
+Notifications
+~~~~~~~~~~~~~
+
+The AlekSIS core has a built-in notification system which can be used by
+apps to send urgent information to specific persons (e. g. timetable
+changes). Notifications are shown on the dashboard and the notifications
+page reachable over the menu entry ``Notifications``. In addition to
+that, notifications can be sent to users through several communication
+channels. These channels can be switched on or off in your personal
+preferences (cf. [@sec:PersonalPreferences]).
+
+Setup two-factor authentication
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+TBA.
+
+Change password
+~~~~~~~~~~~~~~~
+
+If your system administrator has activated this function, you can change
+your password via ``Account → Change password``. If you forgot your
+password, there is a link ``Password forgotten?`` on this page which
+helps with resetting your password. The system then will send you a
+password reset link via email.
+
+Me page
+~~~~~~~
+
+Reachable under ``Account → Me``, this page shows the personal
+information saved about you in the system. If activated, you can upload
+a picture of yourself or edit some information.
+
+.. _sec:PersonalPreferences:
+
+Personal preferences
+~~~~~~~~~~~~~~~~~~~~
+
+You can configure some behavior using the preferences under
+``Account → Preferences``. By default, the Core only provides some
+preferences, but apps can extend this list. You can find further
+information about such preferences in the chapter of the respective
+apps.
+
+-  **Notifications**
+
+   -  **Name format for addressing**: Here you can select how AlekSIS
+      should address you.
+   -  **Channels to use for notifications:** This channel is used to
+      sent notifications to you (cf. [@sec:Notifications]).
+
+Third-party accounts
+~~~~~~~~~~~~~~~~~~~~
+
+If you logged in using a third-party account (e. g. a Google or
+Microsoft account), you can manage the connections to these accounts on
+the page ``Account → Third-party accounts``.
+
+Authorized applications
+~~~~~~~~~~~~~~~~~~~~~~~
+
+On the page ``Account → Authorized applications`` you can see all
+external applications you authorized to retreive data about you from
+AlekSIS. That can be services provided by your local institution like a
+chat platform, for example.