Add redirect for framework devtool accessibility support (#12897)

Add `/go/framework-devtool-a11y-support` design doc redirect.

Author: chunhtai

firebase.json

@@ -473,6 +473,7 @@
       { "source": "/go/forge2d-workshop", "destination": "https://codelabs.developers.google.com/codelabs/flutter-flame-forge2d#0", "type": 301 },
       { "source": "/go/form-field-autovalidation", "destination": "https://docs.google.com/document/d/16HAURcOtYAoHntDOEtdGy9KkKSItulG9Ldyjzdaosqo/edit", "type": 301 },
       { "source": "/go/fragment-program-support", "destination": "https://docs.google.com/document/d/1R0qx3znTe_wcKZoeWwkMlgxs1MtrdiPJ_1xiuExZuH0/edit", "type": 301 },
+      { "source": "/go/framework-devtool-a11y-support", "destination": "https://docs.google.com/document/d/1lR0QaojgeprwwAy8Ks57rCPKUQOCCRz7Zh3yybKLOsk/edit?usp=sharing", "type": 301 },
       { "source": "/go/games-revenue", "destination": "https://services.google.com/fh/files/blogs/gaming_ux_and_revenue_optimizations.pdf", "type": 301 },
       { "source": "/go/generated-plugin-registration", "destination": "https://docs.google.com/document/d/17-GIBYMgaoYS_G34w-fL9oe8W_GX70v6X2bhfKSBrdo/edit", "type": 301 },
       { "source": "/go/generating-flutter-localizations", "destination": "https://docs.google.com/document/d/18saQREDwBMPA_svFe9IkU22ljNXsLpYxiy__jzPCzEc/edit", "type": 301 },