Better account name hint

app/src/main/res/values/strings.xml

@@ -43,7 +43,7 @@
     <string name="title_reply_to">Reply to address</string>
     <string name="title_optional">Optional</string>
     <string name="title_account_name">Account name</string>
-    <string name="title_account_name_hint">optional</string>
+    <string name="title_account_name_hint">Used to differentiate folders</string>
     <string name="title_imap">IMAP</string>
     <string name="title_smtp">SMTP</string>
     <string name="title_provider">Provider</string>