Add a FAQ for tshark-args question by @zoulja

docs/FAQ.md

@@ -10,6 +10,7 @@
 * [Termshark's colors are limited...](#termsharks-colors-are-limited)
 * [Where are the config and log files?](#where-are-the-config-and-log-files)
 * [The console is too narrow on Windows](#the-console-is-too-narrow-on-windows)
+* [Can I pass extra arguments to tshark?](#can-i-pass-extra-arguments-to-tshark)
 * [How does termshark use tshark?](#how-does-termshark-use-tshark)
 * [How can I make termshark run without root?](#how-can-i-make-termshark-run-without-root)
 * [How can termshark capture from extcap interfaces with dumpcap?](#how-can-termshark-capture-from-extcap-interfaces-with-dumpcap)
@@ -133,6 +134,15 @@ Unfortunately, the standard console window won't let you increase its size beyon
 
 ![winconsole](/../gh-pages/images/winconsole.png?raw=true)
 
+## Can I pass extra arguments to tshark?
+
+Yes, via `~/.config/termshark/termshark.toml`. Here is an example I use:
+
+```toml
+[main]
+  tshark-args = ["-d","udp.port==2075,cflow","-d","udp.port==9191,cflow","-d","udp.port==2055,cflow","-d","udp.port==2095,cflow"]
+```
+
 ## How does termshark use tshark?
 
 Termshark uses tshark to provide all the data it displays, and to validate display filter expressions. When you give termshark a pcap file, it will run