Docs for v2.7.0 (#322)

* Docs for v2.7.0

* Document named-routes & invoke, polish reverse_proxy

* Storage import/export CLI docs

* Header replacement defer

* Proxy stream closing options, weighted round robin LB policy

src/docs/markdown/caddyfile/directives/invoke.md

@@ -0,0 +1,56 @@
+---
+title: invoke (Caddyfile directive)
+---
+
+# invoke
+
+Invokes a [named route](/docs/caddyfile/concepts#named-routes).
+
+This is useful when paired with HTTP handler directives that have their own in-memory state, or if they are expensive to provision on load. If you have hundreds of sites or more, invoking a named route can help reduce memory usage.
+
+<aside class="tip">
+	
+Unlike [`import`](/docs/caddyfile/directives/import), `invoke` does not support arguments, but you may use [`vars`](/docs/caddyfile/directives/vars) to define variables that can be used within the named route.
+
+</aside>
+
+## Syntax
+
+```caddy-d
+invoke [<matcher>] <route-name>
+```
+
+- **&lt;route-name&gt;** is the name of the previously defined route that should be invoked. If the route is not found, then an error will be triggered.
+
+
+## Examples
+
+Defines a [named route](/docs/caddyfile/concepts#named-routes) with a [`reverse_proxy`](/docs/caddyfile/directives/reverse_proxy) which can be reused in multiple sites, with the same in-memory load balancing state reused for every site.
+
+```caddy
+&(app-proxy) {
+	reverse_proxy app-01:8080 app-02:8080 app-03:8080 {
+		lb_policy least_conn
+		health_uri /healthz
+		health_interval 5s
+	}
+}
+
+# Apex domain allows accessing the app via an /app subpath
+# and the main site otherwise.
+example.com {
+	handle_path /app* {
+		invoke app-proxy
+	}
+
+	handle {
+		root * /srv
+		file_server
+	}
+}
+
+# The app is also accessible via a subdomain.
+app.example.com {
+	invoke app-proxy
+}
+```