Added FAQ

FAQ.md

@@ -144,6 +144,7 @@ FairEmail follows all the best practices for an email client as decribed in [thi
 * [(81) Can you make the background of the original message dark in the dark theme?](#user-content-faq81)
 * [(82) What is a tracking image?](#user-content-faq82)
 * [(83) What does 'User is authenticated but not connected' mean?](#user-content-faq83)
+* [(84) What are local contacts for?](#user-content-faq84)
 
 [I have another question.](#support)
 
@@ -1364,6 +1365,18 @@ So, double check the password or reduce the number of folders to synchronize.
 
 <br />
 
+<a name="faq84"></a>
+**(84) What are local contacts for?**
+
+The main use of the local contacts storage is to offer auto completion when no contacts permission is of can be granted to FairEmail.
+
+Another use is to generate [shortcuts](#user-content-faq31) on recent Android versions to quickly send a message to frequently contacted people.
+This is also why the number of times contacted and the last time contacted is recorded and why you can make a contact a favorite or exclude it by long pressing it.
+
+The list of contacts is sorted on number of times contacted and the last time contacted.
+
+<br />
+
 ## Support
 
 If you have another question, want to request a feature or report a bug, you can use [this forum](https://forum.xda-developers.com/android/apps-games/source-email-t3824168).