[ADD] API docu

docs/development/custom/framework/api.md

@@ -4,8 +4,37 @@
 
 ### get_main_character_from_user
 
+This is to get the main character object (`EveCharacter`) of a user.
+
+Given we have a `User` object called `my_user` and we want to get the main character:
+
+```python
+# Alliance Auth
+from allianceauth.framework.api.user import get_main_character_from_user
+
+main_character = get_main_character_from_user(user=my_user)
+```
+
+Now, `main_character` is an `EveCharacter` object, or `None` if the user has no main
+character or the user is `None`.
+
 ### get_main_character_name_from_user
 
+This is to get the name of the main character of a user.
+
+Given we have a `User` object called `my_user` and we want to get the main character name:
+
+```python
+# Alliance Auth
+from allianceauth.framework.api.user import get_main_character_name_from_user
+
+main_character = get_main_character_name_from_user(user=my_user)
+```
+
+Now, `main_character` is a `string` containing the user's main character name.
+If the user has no main character, the username will be returned. If the user is `None`,
+the sentinel username (see [get_sentinel_user](#get-sentinel-user)) will be returned.
+
 ### get_sentinel_user
 
 This function is useful in models when using `User` model-objects as foreign keys.
@@ -15,6 +44,7 @@ deleted. To keep the data, you can have Django map this to the sentinel user.
 Import:
 
 ```python
+# Alliance Auth
 from allianceauth.framework.api.user import get_sentinel_user
 ```