docs: document agent.disabled_toolsets config + AUTHOR_MAP

Follow-up to the salvaged PR #16867 that added the read path for
agent.disabled_toolsets in _get_platform_tools():

- Document the new config key under a "Global Toolset Disable" section
  in website/docs/user-guide/configuration.md, including the precedence
  note (global disable overrides per-platform platform_toolsets).
- Map nazirulhafiy@gmail.com -> nazirulhafiy in scripts/release.py
  AUTHOR_MAP so release-notes CI attributes the cherry-picked commit.

scripts/release.py

@@ -68,6 +68,7 @@ AUTHOR_MAP = {
     "itonov@proton.me": "Ito-69",
     "glesstech@gmail.com": "georgeglessner",
     "maxim.smetanin@gmail.com": "maxims-oss",
+    "nazirulhafiy@gmail.com": "nazirulhafiy",
     "CREWorx@users.noreply.github.com": "BadTechBandit",
     "yoimexex@gmail.com": "Yoimex",
     "6548898+romanornr@users.noreply.github.com": "romanornr",