dyncfg: clarify that Environment is not environmentd

Name the coarsest targeting granularity, not the process. balancerd's configs
are Environment because balancerd resolves them against its own regional
LaunchDarkly context, with nothing finer beneath it, not because balancerd is
lumped in with environmentd.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RZo8dwEyXbXwUq6wb7BkeU

Author: claude

src/dyncfg/src/lib.rs

@@ -87,8 +87,11 @@ use tracing::error;
 ///   [`Config::get_with_overrides`] or from a per-replica config set. Without
 ///   that, the override never takes effect and the declaration is a silent
 ///   no-op.
-/// - A config realized in `environmentd` (or `balancerd`) with no single replica
-///   in scope is [`Environment`].
+/// - A config realized in `environmentd` with no single replica in scope is
+///   [`Environment`]. So is every `balancerd` config. `balancerd` syncs
+///   LaunchDarkly itself, against a `balancer` context keyed by cloud provider,
+///   region and build version, and has no environment, cluster or replica
+///   beneath it to target.
 /// - A config consumed at plan time, once per cluster, is [`Cluster`].
 ///
 /// NOTE: a config whose value must agree across the replicas of one cluster
@@ -103,6 +106,10 @@ use tracing::error;
 pub enum ParameterScope {
     /// Environment-wide only; no cluster/replica overrides. The default, so all
     /// existing synced parameters are unchanged.
+    ///
+    /// NOTE: this names the coarsest targeting granularity, not the
+    /// `environmentd` process. A config a process other than `environmentd`
+    /// resolves for itself, with nothing finer beneath it, is `Environment`.
     Environment,
     /// Cluster-coherent: env-wide base plus per-cluster overrides. Evaluated
     /// with the `cluster` context (replica-free) and resolved at plan time via