[vte] docs: Add regex flag requirements

[Christian Persch <chpe src gnome org>]

commit b9adc08edf2899b7f66fa03a86eb0f208c69a6bd
Author: Christian Persch <chpe src gnome org>
Date:   Sun Mar 29 23:27:57 2020 +0200

    docs: Add regex flag requirements
    
    Fixes: https://gitlab.gnome.org/GNOME/vte/issues/223

 src/vtegtk.cc | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/vtegtk.cc b/src/vtegtk.cc
index 8f879512..5808a210 100644
--- a/src/vtegtk.cc
+++ b/src/vtegtk.cc
@@ -2277,6 +2277,8 @@ vte_terminal_hyperlink_check_event(VteTerminal *terminal,
  * text is stored in @matches at the position of the regex in @regexes; otherwise
  * %NULL is stored there.
  *
+ * Note that the regexes in @regexes should have been created using the %PCRE2_MULTILINE flag.
+ *
  * Returns: %TRUE iff any of the regexes produced a match
  *
  * Since: 0.46