[FormControlRange] Update WHATWG issue link (#1160)

Updating the link to the WHATWG tracking issue to the latest version (thanks for catching it, Ana!)

Author: stephanieyzhang

FormControlRange/explainer.md

@@ -8,7 +8,7 @@
 
 ## Participate
 
-- [WHATWG tracking issue](https://github.com/whatwg/html/issues/10614)
+- [WHATWG tracking issue](https://github.com/whatwg/html/issues/11478)
 - [CSSWG issue tracking initial discussions](https://github.com/w3c/csswg-drafts/issues/10346)
 - [TPAC 2024 WHATWG meeting minutes on initial proposal](https://github.com/whatwg/meta/issues/326#issuecomment-2377500295)
 - [Issue tracker](https://github.com/MicrosoftEdge/MSEdgeExplainers/labels/FormControlRange)