chore: add metadata labels to Dockerfiles (#4811)

Signed-off-by: Rowan Ruseler <rowanruseler@gmail.com>
Signed-off-by: Rowan Ruseler <rowan@miro.com>

Dockerfile

@@ -1,4 +1,9 @@
 FROM gcr.io/distroless/static@sha256:d9f9472a8f4541368192d714a995eb1a99bab1f7071fc8bde261d7eda3b667d8
+
+# Add metadata
+LABEL maintainer="cncf-externalsecretsop-maintainers@lists.cncf.io" \
+      description="External Secrets Operator is a Kubernetes operator that integrates external secret management systems"
+
 ARG TARGETOS
 ARG TARGETARCH
 COPY bin/external-secrets-${TARGETOS}-${TARGETARCH} /bin/external-secrets

Dockerfile.standalone

@@ -1,6 +1,9 @@
 # This version of Dockerfile is for building without external dependencies.
 # Build a multi-platform image e.g. `docker buildx build --push --platform linux/arm64,linux/amd64 --tag external-secrets:dev --file Dockerfile.standalone .`
 FROM golang:1.24.3-alpine@sha256:ef18ee7117463ac1055f5a370ed18b8750f01589f13ea0b48642f5792b234044 AS builder
+# Add metadata
+LABEL maintainer="cncf-externalsecretsop-maintainers@lists.cncf.io" \
+      description="External Secrets Operator is a Kubernetes operator that integrates external secret management systems"
 ARG TARGETOS
 ARG TARGETARCH
 ENV CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH}

Dockerfile.ubi

@@ -1,5 +1,9 @@
 FROM registry.access.redhat.com/ubi8/ubi@sha256:244e9858f9d8a2792a3dceb850b4fa8fdbd67babebfde42587bfa919d5d1ecef AS minimal-ubi
 
+# Add metadata
+LABEL maintainer="cncf-externalsecretsop-maintainers@lists.cncf.io" \
+      description="External Secrets Operator is a Kubernetes operator that integrates external secret management systems"
+
 ARG TARGETOS
 ARG TARGETARCH
 RUN dnf update -y && dnf install -y binutils