Update upgrade.md (docker#8887)

Author: scjane

docker-hub/upgrade.md

@@ -14,7 +14,7 @@ plan.
 
 To upgrade:
 1. Visit the [Plans Page](https://hub.docker.com/account/billing-plans/)
-2. Click Change Plan
+2. Click **Change Plan**
 3. Select your plan and provide your payment information to upgrade ![Upgrade Plan](images/index-upgrade-plan.png)
 
 ### Upgrade your organization's plan
@@ -24,4 +24,4 @@ To upgrade an Organization's plan:
 1. Visit the [Plans Page](https://hub.docker.com/account/billing-plans/)
 2. Change the selected account to your Organization whose plan you'd like to upgrade ![Change Account](images/upgrade-change-account.png)
 
-3. Click Change Plan ![Change Plan](images/upgrade-change-plan.png)
+3. Click **Change Plan** ![Change Plan](images/upgrade-change-plan.png)