Updated FAQ

FAQ.md

@@ -811,7 +811,22 @@ Words separated by commas result in searching for OR, so for example *apple, ora
 Both can be combined, so searching for *apple, orange banana* will search for apple OR (orange AND banana).
 Using the search index is a pro feature.
 
-Searching messages on the device is a free feature, searching messages on the server is a pro feature.
+From version 1.1315 it is possible to use search expressions like this:
+
+```
+apple +banana -cherry ?nuts
+```
+
+This will result in searching like this:
+
+```
+("apple" AND "banana" AND NOT "cherry") OR "nuts"
+```
+
+Search expressions can be used for searching on the device via the search index and for searching on the email server,
+but not for searching on the device without search index for performance reasons.
+
+Searching on the device is a free feature, using the search index and searching on the server is a pro feature.
 
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