[pango/ricotz/parse-color-with-alpha] Fix g-i annotation of pango_parse_color_with_alpha and add since tag

[Rico Tzschichholz <ricotz src gnome org>]

commit 8746587205a85afe9cec580262b6f99bc73703f8
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Tue Aug 4 15:33:27 2020 +0200

    Fix g-i annotation of pango_parse_color_with_alpha and add since tag

 pango/pango-color.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/pango/pango-color.c b/pango/pango-color.c
index 9c044810a..a530719fc 100644
--- a/pango/pango-color.c
+++ b/pango/pango-color.c
@@ -211,7 +211,7 @@ hex (const char *spec,
  * pango_color_parse_with_alpha:
  * @color: (nullable): a #PangoColor structure in which to store the
  *   result, or %NULL
- * @alpha: (nullable): return location for alpha, or %NULL
+ * @alpha: (out) (optional): return location for alpha, or %NULL
  * @spec: a string specifying the new color
  *
  * Fill in the fields of a color from a string specification. The
@@ -231,6 +231,8 @@ hex (const char *spec,
  *
  * Return value: %TRUE if parsing of the specifier succeeded,
  *   otherwise false.
+ *
+ * Since: 1.46
  */
 gboolean
 pango_color_parse_with_alpha (PangoColor *color,