add headings for user guides

source/guides/access-calendar-feeds.rst

+========================
+List available calendars
+========================
+
+
 .. _access-calendar-feeds:
 
-Access calendar feeds
-=====================
 
 Access the calendar feeds overview page
----------------------------------------
+=======================================
 
 add "/feeds/" to the URL of the castellum start page and confirm.
 
 Find the different types of calendars
--------------------------------------
+=====================================
 
 1.  Under "Per User" find user-specific feeds:
 
@@ -23,7 +26,7 @@ Find the different types of calendars
     -   The list of resources is configurable by your institution (TODO link to resources guide)
 
 Reset user tokens
------------------
+=================
 
 Each calendar feed URL contains a token that uniquely identifies you so you can
 access feeds that would not be available to other users.

source/guides/appointments-external-scheduler.rst

+=================================
+Appointments: External scheduling
+=================================
+
+
 .. _set-up-external-scheduler:
 
 Set up an external scheduler for appointments

source/guides/consent-management.rst

+=============================
+Managing recruitment consents
+=============================
+
+
 .. _subject-consent:
 
 Set Recruitment Consent for a Subject

source/guides/data-protection.rst

+==========================
+Data protection: workflows
+==========================
+
+
 .. _data-protection-dashboard:
 
 Use the data protection dashboard

source/guides/pseudonyms.rst

+====================
+Pseudonym management
+====================
+
+
 .. _subject-by-pseudonym:
 
 Find subject by study pseudonym

source/guides/recruitment.rst

+=================
+Study recruitment
+=================
+
+
 .. _recruitment:
 
 Recruit subjects via phone

source/guides/study-management.rst

+================
+Study management
+================
+
+
 .. _study-create:
 
 Create a study

source/guides/subject-management.rst

+==================
+Subject management
+==================
+
+
 .. _subject-search:
 
 Search for a subject

source/guides/two-factor-authentication.rst

+=====================
+Secure authentication
+=====================
+
+
 .. _2fa:
 
 Two-Factor-Authentication