[gtk/gtk-4-6] docs: Fix typo in description of GtkExpression

[Matthias Clasen <matthiasc src gnome org>]

commit e449bd8459afcd247f52c9276a2016328c3fc292
Author: Marcel Tiede <33569-badcel users noreply gitlab gnome org>
Date:   Mon Apr 18 06:20:19 2022 +0000

    docs: Fix typo in description of GtkExpression

 gtk/gtkexpression.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkexpression.c b/gtk/gtkexpression.c
index 14bea1111b..8750782bdd 100644
--- a/gtk/gtkexpression.c
+++ b/gtk/gtkexpression.c
@@ -125,7 +125,7 @@
  * a `GtkExpression` object is needed like in a `<property>` tag for an expression
  * property, or in a `<binding name="property">` tag to bind a property to an expression.
  *
- * To create an property expression, use the `<lookup>` element. It can have a `type`
+ * To create a property expression, use the `<lookup>` element. It can have a `type`
  * attribute to specify the object type, and a `name` attribute to specify the property
  * to look up. The content of `<lookup>` can either be an element specfiying the expression
  * to use the object, or a string that specifies the name of the object to use.