docs/windows/policy: add ExitNode.AllowOverride as an option to ExitNodeID policy

In this PR, we make ExitNode.AllowOverride configurable as part of the Exit Node ADMX policy setting,
similarly to Always On w/ "Disconnect with reason" option.

Updates tailscale/corp#29969

Signed-off-by: Nick Khyl <nickk@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f