INSTALL.md: update contacts sync section

The DAVDroid app was renamed to DAVx5 a while ago.

INSTALL.md

@@ -164,9 +164,9 @@ You can retieve your contacts directly from your Google account in a vcf file:
  - Go to [Google Contacts](https://contacts.google.com) and login
  - Use sidebar > Export > select 'Export as VCard' > Export
 
-You should also be able to sync contacts with Google without proprietary apps or microG using the open-source CardDAV client DAVdroid (available on F-Droid or Play)
+You should also be able to sync contacts with Google without proprietary apps or microG using the open-source CardDAV client DAVx5 (available on F-Droid or Play)
  - Go to Google Dashboard's [app passwords](https://myaccount.google.com/apppasswords) page, and create an app password if you don't have one already
- - When logging in with DAVDroid, Use "Login with URL and user name"
+ - When logging in with DAVx5, Use "Login with URL and user name"
    - Base URL: `https://www.google.com/calendar/dav/[your_gmail_id]@gmail.com/events`
    - User name: `[your_gmail_id]@gmail.com`
    - Password: `[your_app_password]`