[gtk/matthiasc/for-master: 23/41] docs: Update GSK_RENDERER docs

[Matthias Clasen <matthiasc src gnome org>]

commit fc9f580fd397c065c08f7d7dc50a4fbf3d285d31
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat May 22 13:09:54 2021 -0400

    docs: Update GSK_RENDERER docs
    
    This did not mention the opengl and ngl values yet.

 docs/reference/gtk/running.md | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/docs/reference/gtk/running.md b/docs/reference/gtk/running.md
index 3a3458eb1d..bd798341d2 100644
--- a/docs/reference/gtk/running.md
+++ b/docs/reference/gtk/running.md
@@ -324,9 +324,15 @@ using and the GDK backend supports them:
 `cairo`
 : Selects the fallback Cairo renderer
 
-`gl`
+`opengl`
 : Selects the default OpenGL renderer
 
+`gl`
+: Selects the "gl" OpenGL renderer
+
+`ngl`
+: Selects the "ngl" OpenGL renderer
+
 `vulkan`
 : Selects the Vulkan renderer