Add documentation for geo pause commands

- Add documentation for pausing/resuming replication
- Add link to page as a part of upgrade docs

Relates to https://gitlab.com/gitlab-org/gitlab/issues/35913

doc/administration/geo/replication/index.md

@@ -213,6 +213,26 @@ For information on configuring Geo, see [Geo configuration](configuration.md).
 
 For information on how to update your Geo nodes to the latest GitLab version, see [Updating the Geo nodes](updating_the_geo_nodes.md).
 
+### Pausing and resuming replication
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/35913) in [GitLab Premium](https://about.gitlab.com/pricing/) 13.2.
+
+In some circumstances, like during [upgrades](updating_the_geo_nodes.md) or a [planned failover](../disaster_recovery/planned_failover.md), it is desirable to pause replication between the primary and secondary.
+
+Pausing and resuming replication is done via a command line tool from the secondary node.
+
+**To Pause: (from secondary)**
+
+```shell
+gitlab-ctl geo-replication-pause
+```
+
+**To Resume: (from secondary)**
+
+```shell
+gitlab-ctl geo-replication-resume
+```
+
 ### Configuring Geo for multiple servers
 
 For information on configuring Geo for multiple servers, see [Geo for multiple servers](multiple_servers.md).

doc/administration/geo/replication/updating_the_geo_nodes.md

@@ -41,10 +41,12 @@ NOTE: **Note:** These general update steps are not intended for [high-availabili
 To update the Geo nodes when a new GitLab version is released, update **primary**
 and all **secondary** nodes:
 
+1. **Optional:** [Pause replication on each **secondary** node.](./index.md#pausing-and-resuming-replication)
 1. Log into the **primary** node.
 1. [Update GitLab on the **primary** node using Omnibus](https://docs.gitlab.com/omnibus/update/README.html).
 1. Log into each **secondary** node.
 1. [Update GitLab on each **secondary** node using Omnibus](https://docs.gitlab.com/omnibus/update/README.html).
+1. If you paused replication in step 1, [resume replication on each **secondary**](./index.md#pausing-and-resuming-replication)
 1. [Test](#check-status-after-updating) **primary** and **secondary** nodes, and check version in each.
 
 ### Check status after updating