Merge pull request #3979 from ClickHouse/krithika-ch-patch-6

Update upgrades.md

Author: Blargian

docs/cloud/manage/upgrades.md

@@ -39,7 +39,16 @@ You will not be charged for the time that the service is under maintenance. _Mai
 
 ## Release channels (upgrade schedule) {#release-channels-upgrade-schedule}
 
-You are able to specify the upgrade schedule for your ClickHouse Cloud service by subscribing to a specific release channel.
+Users are able to specify the upgrade schedule for their ClickHouse Cloud service by subscribing to a specific release channel. There are three release channels, and the user has the ability to configure the day and time of the week for upgrades with the **scheduled upgrades** feature.
+
+The three release channels are:
+- The [**fast release channel**](#fast-release-channel-early-upgrades) for early access to upgrades.
+- The [**regular release channel**](#regular-release-channel) is the default, and upgrades on this channel start two weeks after the fast release channel upgrades. If your service on the Scale and Enterprise tier does not have a release channel set, it is on the regular release channel by default.
+- The [**slow release channel**](#slow-release-channel-deferred-upgrades) is for deferred release. Upgrades on this channel occur two weeks after the regular release channel upgrades.
+
+:::note
+Basic tier services are automatically enlisted to the fast release channel
+:::
 
 ### Fast release channel (early upgrades) {#fast-release-channel-early-upgrades}
 
@@ -76,6 +85,18 @@ Upgrades to the regular release channel are typically performed two weeks after
 Basic tier services are upgraded soon after the Fast release channel.
 :::
 
+### Slow release channel (deferred upgrades) {#slow-release-channel-deferred-upgrades}
+
+<EnterprisePlanFeatureBadge feature="The slow release channel"/>
+
+We offer a **Slow release** channel if you would like your services to receive upgrades after the regular release schedule.
+
+Specifically, services will:
+
+- Be upgraded after the Fast and Regular release channels roll-outs are complete
+- Receive ClickHouse releases ~ 2 weeks after the regular release
+- Be meant for customers that want additional time to test ClickHouse releases on their non-production environments before the production upgrade. Non-production environments can either get upgrades on the Fast or the Regular release channel for testing and validation.
+
 ## Scheduled upgrades {#scheduled-upgrades}
 
 <EnterprisePlanFeatureBadge feature="Scheduled upgrades" linking_verb_are="true"/>