Remove CraftSpider from review rotation

CraftSpider was removed from the rustdoc team in rust-lang/team#897 and can no longer be assigned.

Author: ehuss

triagebot.toml

@@ -496,7 +496,6 @@ infra-ci = [
 rustdoc = [
     "@jsha",
     "@GuillaumeGomez",
-    "@CraftSpider",
     "@notriddle",
 ]
 docs = [