[mutter] Use correct ASCII character for degree

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 3f9ff187514c28812077e287b906adb6c67af682
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Oct 15 11:16:55 2020 +0000

    Use correct ASCII character for degree

 Clutter-Rendering-Model.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Clutter-Rendering-Model.md b/Clutter-Rendering-Model.md
index 0fb9500..8b2194a 100644
--- a/Clutter-Rendering-Model.md
+++ b/Clutter-Rendering-Model.md
@@ -16,7 +16,7 @@ When setting up the projection, ClutterStage uses a traditional perspective proj
  * **aspect**: width / height (depends on monitor configuration)
  * **z-near**: 1.0 (hardcoded)
  * **z-2d**: `z-near + z-near * 49,36` ( = 50,36)
- * **z-far**: `z-2d + z-2d * tan(30º) * 20` ( = 631,97)
+ * **z-far**: `z-2d + z-2d * tan(30°) * 20` ( = 631,97)
 
 ![view_cone](uploads/bb933041d1ea66813411e5da78b54eca/view_cone.png)