Add/update description metadata on backend and state overview pages

website/docs/language/settings/backends/index.html.md

@@ -1,6 +1,8 @@
 ---
 layout: "language"
 page_title: "Backend Overview - Configuration Language"
+description: |-
+  An introduction to Terraform configuration backends.
 ---
 
 # Backends

website/docs/language/state/index.html.md

@@ -3,7 +3,7 @@ layout: "language"
 page_title: "State"
 sidebar_current: "docs-state"
 description: |-
-  Terraform must store state about your managed infrastructure and configuration. This state is used by Terraform to map real world resources to your configuration, keep track of metadata, and to improve performance for large infrastructures.
+  An introduction to state, information that Terraform uses to map resources to a configuration, track metadata, and improve performance.
 ---
 
 # State