add deprecation notices to backends

website/docs/language/settings/backends/artifactory.mdx

@@ -3,7 +3,9 @@ page_title: 'Backend Type: artifactory'
 description: Terraform can store state in artifactory.
 ---
 
-# artifactory
+# artifactory (deprecated)
+
+~> **NOTE:** The `artifactory` backend is deprecated, and will be removed in a future Terraform release.
 
 Stores the state as an artifact in a given repository in
 [Artifactory](https://www.jfrog.com/artifactory/).

website/docs/language/settings/backends/etcd.mdx

@@ -3,7 +3,9 @@ page_title: 'Backend Type: etcd'
 description: Terraform can store state remotely in etcd 2.x.
 ---
 
-# etcd
+# etcd (deprecated)
+
+~> **NOTE:** The `etcd` backend is deprecated, and will be removed in a future Terraform release.
 
 Stores the state in [etcd 2.x](https://coreos.com/etcd/docs/latest/v2/README.html) at a given path.
 

website/docs/language/settings/backends/etcdv3.mdx

@@ -3,7 +3,9 @@ page_title: 'Backend Type: etcdv3'
 description: Terraform can store state remotely in etcd 3.x.
 ---
 
-# etcdv3
+# etcdv3 (deprecated)
+
+~> **NOTE:** The `etcdv3` backend is deprecated, and will be removed in a future Terraform release.
 
 Stores the state in the [etcd](https://etcd.io/) KV store with a given prefix.
 

website/docs/language/settings/backends/manta.mdx

@@ -3,7 +3,9 @@ page_title: 'Backend Type: manta'
 description: Terraform can store state in manta.
 ---
 
-# manta
+# manta (deprecated)
+
+~> **NOTE:** The `manta` backend is deprecated, and will be removed in a future Terraform release.
 
 Stores the state as an artifact in [Manta](https://www.joyent.com/manta).
 

website/docs/language/settings/backends/swift.mdx

@@ -3,7 +3,9 @@ page_title: 'Backend Type: swift'
 description: Terraform can store state remotely in Swift.
 ---
 
-# swift
+# swift (deprecated)
+
+~> **NOTE:** The `swift` backend is deprecated, and will be removed in a future Terraform release.
 
 Stores the state as an artifact in [Swift](http://docs.openstack.org/developer/swift/latest/).