Fix %ex{short} docs

Author: vy

src/site/antora/modules/ROOT/pages/manual/pattern-layout.adoc

@@ -624,7 +624,7 @@ If this mode is employed without any configuration, the output will be identical
 
 `none`:: Suppress the output of the converter
 
-`short`:: Outputs the first line of the stack trace (analogous to `%ex\{1}`)
+`short`:: Outputs the first two lines of the stack trace (analogous to `%ex\{2}`)
 
 `depth`:: Outputs the first `depth` lines of the stack trace (`%ex\{0}` is analogous to `%ex\{none}`)