[pango] Update docs

[Matthias Clasen <matthiasc src gnome org>]

commit aae5fa3d34f021a3dcf8663d55f4fec19e9f7aff
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Nov 8 15:08:03 2021 -0500

    Update docs
    
    Add the new variant values to the docs.

 pango/fonts.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/pango/fonts.c b/pango/fonts.c
index 70a987e6..9d3c1bf3 100644
--- a/pango/fonts.c
+++ b/pango/fonts.c
@@ -1270,7 +1270,8 @@ parse_variations (const char  *word,
  * "Normal", "Roman", "Oblique", "Italic".
  *
  * The following words are understood as variants:
- * "Small-Caps".
+ * "Small-Caps", "All-Small-Caps", "Petite-Caps", "All-Petite-Caps",
+ * "Unicase", "Title-Caps".
  *
  * The following words are understood as weights:
  * "Thin", "Ultra-Light", "Extra-Light", "Light", "Semi-Light",