Add docs for Let's Encrypt integration

* Add deprecation warning to old integration
* Add user docs
* Add admin docs

2 files changed, 17 insertions, 0 deletions

diff --git a/doc/administration/pages/img/lets_encrypt_integration_v12_1.png b/doc/administration/pages/img/lets_encrypt_integration_v12_1.png
new file mode 100644
index 00000000000..5ab63074e12
--- /dev/null
+++ b/doc/administration/pages/img/lets_encrypt_integration_v12_1.png
diff --git a/doc/administration/pages/index.md b/doc/administration/pages/index.md
index 3cabe8eb16e..774e7056845 100644
--- a/doc/administration/pages/index.md
+++ b/doc/administration/pages/index.md
@@ -265,6 +265,23 @@ verification requirement. Navigate to `Admin area ➔ Settings` and uncheck
 **Require users to prove ownership of custom domains** in the Pages section.
 This setting is enabled by default.
 
+### Let's Encrypt integration
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/28996) in GitLab 12.1.
+
+[GitLab Pages' Let's Encrypt integration](../../user/project/pages/custom_domains_ssl_tls_certification/lets_encrypt_integration.md)
+allows users to add Let's Encrypt SSL certificates for GitLab Pages
+sites served under a custom domain.
+
+To enable it, you'll need to:
+
+1. Choose an email on which you will recieve notifications about expiring domains.
+1. Navigate to your instance's **Admin Area > Settings > Preferences** and expand **Pages** settings.
+1. Enter the email for receiving notifications and accept Let's Encrypt's Terms of Service as shown below.
+1. Click **Save changes**.
+
+![Let's Encrypt settings](img/lets_encrypt_integration_v12_1.png)
+
 ### Access control
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/33422) in GitLab 11.5.