Drop reference to clutter in robustness

Drop references to clutter from the robustness document

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

content/concepts/robustness.md

@@ -14,7 +14,7 @@ date = "2016-05-28"
 lastmod = "2021-12-03"
 
 status = "Update required"
-statusDescription = "Covers BTRFS which we no longer use. Main storage section covers shutdown sequence that seems suspiciously hardware dependent, but does not describe platform. Describes use of WebKit-Clutter. Discussion of use of WebGL may be out of date."
+statusDescription = "Covers BTRFS which we no longer use. Main storage section covers shutdown sequence that seems suspiciously hardware dependent, but does not describe platform. Discussion of use of WebGL may be out of date."
 +++
 
 #  Introduction
@@ -541,7 +541,7 @@ important to ensure that their ability to disrupt system functionality
 is minimised. For this, WebKit can detect when a block of JavaScript
 code has been executing for too long, pause it, and give the embedding
 application the possibility of canceling the execution of this block of
-code. Collabora has added API to WebKit-Clutter for this.
+code.
 
 ###  I/O