[pango/deprecate-pango-script] Add a note to pango_language_get_scripts docs

[Matthias Clasen <matthiasc src gnome org>]

commit 3883d19990415d03d247bc6cbf8f344e2160db88
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 27 14:38:09 2019 +0000

    Add a note to pango_language_get_scripts docs
    
    Explain that returned script values are, in fact,
    from the GUnicodeScript enumeration.

 pango/pango-language.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/pango/pango-language.c b/pango/pango-language.c
index 725559fa..0c195844 100644
--- a/pango/pango-language.c
+++ b/pango/pango-language.c
@@ -638,6 +638,10 @@ pango_language_get_sample_string (PangoLanguage *language)
  * The pango_language_includes_script() function uses this function
  * internally.
  *
+ * Note: while the return value is declared as PangoScript, the
+ * returned values are from the GUnicodeScript enumeration, which
+ * may have more values. Callers need to handle unknown values.
+ *
  * Return value: (array length=num_scripts) (nullable): An array of
  * #PangoScript values, with the number of entries in the array stored
  * in @num_scripts, or %NULL if Pango does not have any information