website: Add docs/internals/archiving.html to describe the archiving process. (#18831)

Add docs/internals/archiving.html to describe the archiving process.

website/docs/internals/archiving.html.md

@@ -0,0 +1,28 @@
+---
+layout: "docs"
+page_title: "Archiving Providers"
+sidebar_current: "docs-internals"
+description: |-
+  Terraform is built on a plugin-based architecture, much of which is maintained by our user community. Occasionally, unmaintained providers may archived to reduce confusion for users and developers.
+---
+
+<!--
+This page is purposefully not linked from anywhere on terraform.io: it is intended to be linked only from the README files of archived providers.
+-->
+
+# Archiving Providers
+
+As contributors' circumstances change, development on a community-maintained Terraform provider can slow. When this happens, HashiCorp may use GitHub's "archiving" feature on the provider's repository, to clearly signal the provider's status to users.
+
+What does archiving mean?
+
+1. The code repository and all commit, issue, and PR history will still be available.
+1. Existing released binaries will remain available on the releases site.
+1. Documentation for the provider will remain on the Terraform website.
+1. Issues and pull requests are not being monitored, merged, or added.
+1. No new releases will be published.
+1. Nightly acceptance tests may not be run.
+
+HashiCorp may archive a provider when we or the community are not able to support it at a level consistent with our open source guidelines and community expectations.
+
+Archiving is reversible. If anyone from the community is willing to maintain an archived provider, please reach out to the [Terraform Provider Development Program](https://www.terraform.io/guides/terraform-provider-development-program.html) at *terraform-provider-dev@hashicorp.com*.