Update proposed.md

Updating proposed SIGS, removing Storage as it's an active SIG now

sigs/proposed.md

@@ -7,5 +7,5 @@
 | Governance | security, authentication, authorization, auditing, policy enforcement, compliance, GDPR, cost management, etc. | SPIFFE, SPIRE, Open Policy Agent, Notary, TUF, Falco
 | App Dev, Ops & Testing | PaaS, Serverless, Operators, CI/CD, Conformance, Chaos Eng, Scalability and Reliability measurement etc. | Helm, CloudEvents, Telepresence, Buildpacks
 | Core and Applied Architectures | orchestration, scheduling, container runtimes, sandboxing technologies, packaging and distribution, specialized architectures thereof (e.g. Edge, IoT, Big Data, AI/ML, etc). | Kubernetes, containerd, rkt, Harbor, Dragonfly, Virtual Kubelet
-| Storage | Block, File and Object Stores, Databases, Key-Value stores, etc. | TiKV, etcd, Vitess, Rook
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