Add rustdoc to src/tools/rustdoc*

Author: ehuss

highfive/configs/rust-lang/rust.json

@@ -46,6 +46,10 @@
         "src/tools/linkchecker":    ["@ehuss"],
         "src/tools/rust-installer": ["@Mark-Simulacrum"],
         "src/tools/rustbook":       ["doc", "@ehuss"],
+        "src/tools/rustdoc":        ["rustdoc"],
+        "src/tools/rustdoc-js":     ["rustdoc"],
+        "src/tools/rustdoc-js-std": ["rustdoc"],
+        "src/tools/rustdoc-themes": ["rustdoc"],
         "src/tools/tidy":           ["@Mark-Simulacrum"],
         "src/ci":                   ["infra-ci"],
         ".azure-pipelines":         ["infra-ci"],