chore: import upstream snapshot with attribution

internal/website/docs/registry.md

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+---
+layout: default
+---
+
+# Registry
+
+<img src="/images/generated/registry.jpg" alt="Registry" style="width: 100%; border-radius: 8px; margin: 1rem 0 1.5rem;" />
+
+The registry is responsible for service discovery in Go Micro. It allows services to register themselves and discover other services.
+
+## Features
+- Service registration and deregistration
+- Service lookup
+- Watch for changes
+
+## Implementations
+Go Micro supports multiple registry backends, including:
+- MDNS (default)
+- Consul
+- Etcd
+- NATS
+
+You can configure the registry when initializing your service.
+
+## Plugins Location
+
+Registry plugins live in this repository under `go-micro.dev/v6/registry/<plugin>` (e.g., `consul`, `etcd`, `nats`). Import the desired package and pass it via `micro.Registry(...)`.
+
+## Configure via environment
+
+```
+MICRO_REGISTRY=etcd MICRO_REGISTRY_ADDRESS=127.0.0.1:2379 micro server
+```
+
+Common variables:
+- `MICRO_REGISTRY`: selects the registry implementation (`mdns`, `consul`, `etcd`, `nats`).
+- `MICRO_REGISTRY_ADDRESS`: comma-separated list of registry addresses.
+
+Backend-specific variables:
+- Etcd: `ETCD_USERNAME`, `ETCD_PASSWORD` for authenticated clusters.
+
+## Example Usage
+
+Here's how to use a custom registry (e.g., Consul) in your Go Micro service:
+
+```go
+package main
+
+import (
+    "go-micro.dev/v6"
+    "go-micro.dev/v6/registry/consul"
+)
+
+func main() {
+    reg := consul.NewRegistry()
+    service := micro.NewService("registry-example",
+        micro.Registry(reg),
+    )
+    service.Init()
+    service.Run()
+}
+```