help: Consolidate upgrade steps for self-hosted and cloud billing.

help/include/plan-upgrade-steps.md

@@ -0,0 +1,5 @@
+1. Select your preferred option from the **Payment schedule** dropdown.
+
+1. Click **Add card** to enter your payment details.
+
+1. Click the **Purchase** button to complete your purchase.

help/self-hosted-billing.md

@@ -96,11 +96,7 @@ organization is considered to be a new customer if:
 1. On the page listing Zulip's self-hosted plans, click the button at the bottom
    of the plan you would like to purchase.
 
-1. Select your preferred option from the **Payment schedule** dropdown.
+{!plan-upgrade-steps.md!}
-
-1. Click **Add card** to enter your payment details.
-
-1. Click the **Purchase** button to complete your purchase.
 
 !!! warn ""
 
@@ -114,11 +110,7 @@ organization is considered to be a new customer if:
 
 {!legacy-log-in.md!}
 
-1. Select your preferred option from the **Payment schedule** dropdown.
+{!plan-upgrade-steps.md!}
-
-1. Click **Add card** to enter your payment details.
-
-1. Click the **Purchase** button to complete your purchase.
 
 {end_tabs}
 

help/zulip-cloud-billing.md

@@ -14,11 +14,7 @@ don't hesitate to reach out at [sales@zulip.com](mailto:sales@zulip.com).
 
 1. Under the **Cloud Standard** pricing plan, click **Upgrade to Standard**.
 
-1. Select your preferred option from the **Payment schedule** dropdown.
+{!plan-upgrade-steps.md!}
-
-1. Click **Add card** to enter your payment details.
-
-1. Click **Purchase Zulip Cloud Standard**.
 
 {tab|zulip-cloud-plus}