Updated FAQ

FAQ.md

@@ -951,6 +951,12 @@ In the *miscellaneous settings* you can enable *Build search index* to significa
 but be aware that this will increase battery and storage space usage.
 The search index is based on words in all message parts,
 so searching for partial text and searching in specific messages parts (from, subject, text, etc) is not possible.
+
+Note that only messages for which the message text was downloaded will be indexed.
+In the connection settings can be configured up to which size messages texts will be downloaded automatically
+when using a metered connection (generally mobile data or paid WiFi).
+In the folder properties (long press on a folder in the folder list of an account) downloading of messages texts can be enabled/disabled.
+
 Searching using the search index is by default AND, so searching for *apple orange* will search for apple AND orange.
 Words separated by commas result in searching for OR, so for example *apple, orange* will search for apple OR orange.
 Both can be combined, so searching for *apple, orange banana* will search for apple OR (orange AND banana).