fix!: rename CLUSTER_DOMAIN env var to FLAGD_CLUSTER_DOMAIN

Documents the breaking env var rename from CLUSTER_DOMAIN to
FLAGD_CLUSTER_DOMAIN introduced in #792.

BREAKING CHANGE: CLUSTER_DOMAIN env var is now FLAGD_CLUSTER_DOMAIN.

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

Author: toddbaert

internal/common/types/envconfig.go

@@ -10,7 +10,8 @@ type EnvConfig struct {
 	FlagdProxyPort           int    `envconfig:"FLAGD_PROXY_PORT" default:"8015"`
 	FlagdProxyManagementPort int    `envconfig:"FLAGD_PROXY_MANAGEMENT_PORT" default:"8016"`
 	FlagdProxyDebugLogging   bool   `envconfig:"FLAGD_PROXY_DEBUG_LOGGING" default:"false"`
-	FlagdClusterDomain       string `envconfig:"FLAGD_CLUSTER_DOMAIN" default:"cluster.local"`
+	// renamed from CLUSTER_DOMAIN to FLAGD_CLUSTER_DOMAIN in 0.8.10
+	FlagdClusterDomain string `envconfig:"FLAGD_CLUSTER_DOMAIN" default:"cluster.local"`
 
 	FlagdImage string `envconfig:"FLAGD_IMAGE" default:"ghcr.io/open-feature/flagd"`
 	// renovate: datasource=github-tags depName=open-feature/flagd/flagd