Update user_manual/groupware/contacts.rst

Co-authored-by: Sebastian Krupinski <165827823+SebastianKrupinski@users.noreply.github.com>
Signed-off-by: Grigory Vodyanov <scratchx@gmx.com>

Author: GVodyanov

user_manual/groupware/contacts.rst

@@ -129,7 +129,7 @@ Merging duplicate Contacts
 
 To merge contacts, select two contacts then click the "Merge contacts" icon button at the top of the contacts list this will open a dialog that helps you merge duplicate contacts. The merging dialog will show the details of both contacts side by side, and you can choose which details to keep in the merged contact.
 
-Radio (circular) buttons let you choose only one of the two versions (like the name of the contact, which can only have one value), meanwhile checkboxes (square buttons) allow you to keep both values if desired (like phone numbers or email addresses, where a contact can have multiple values).
+Any parameters with a Radio (circular) button can only have one value, so one of the two values must be selected (like the name of the contact, which can only have one value), meanwhile checkboxes (square buttons) allow you to keep both values if desired (like phone numbers or email addresses, which can have multiple values).
 
 If the contacts are part of groups, by default the merged contact will be part of all groups that either of the two contacts was part of. You can uncheck groups while merging if you don't want the merged contact to be part of them.