cli: describe --continue in more detail

cli/commandadd.cpp

@@ -16,7 +16,10 @@
 int CommandAdd::handle(QStringList arguments)
 {
 	QCommandLineParser parser;
-	parser.addOptions({{{"c", "continue"}, "Continue adding files, don't exit on first error"},
+	parser.addOptions({{{"c", "continue"},
+						"Continue adding files, don't exit on first error. If this option is not given, qss will exit "
+						"asap, but it's possible that a few files will still be processed. "
+						"Set -t 1 to avoid this behavior, but processing will be slower. "},
 					   {{"a", "all"}, "On error, no files should be added, even already processed ones"},
 					   {{"v", "verbose"}, "Print skipped and added files"},
 					   {{"t", "threads"}, "Number of threads to use.", "threads"}});