[gndoc] Update GN build arguments documentation

Roller-URL: https://ci.chromium.org/b/8850085857651322704
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Change-Id: I260fce1f5f3400d8be0ffd36a7d232e21754adc3
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diff --git a/docs/gen/build_arguments.md b/docs/gen/build_arguments.md
index a439187..e665ec3 100644
--- a/docs/gen/build_arguments.md
+++ b/docs/gen/build_arguments.md
@@ -3017,7 +3017,7 @@
 When using the prebuilt, this is ignored and the CIPD instance ID of the
 prebuilt is used.
 
-**Current value (from the default):** `"zlth2Vwh8AafQ2nu6NhLVhOq07bDg98afOzh7hxmxA0C"`
+**Current value (from the default):** `"WEl9a67yLwXf_jo-OMCiXuNyK5HsgUv-gQVD6N5S9pEC"`
 
 From //build/rust/config.gni:32