Merge pull request #594 from humanmade/backport-592-to-v21-branch

[Backport v21-branch] Improve wording on the upgrade guide

Author: mikelittle

other-docs/guides/upgrading/v21.md

@@ -82,7 +82,7 @@ Altis Cloud now offers Backup Shipping, an add-on service designed for customers
 and disaster recovery. Adhering to the industry-standard 3-2-1 rule, this feature enables users to retain three copies of data
 across two storage types, with one copy stored off-site. Contact your account manager for more information.
 
-As always, we continue to incorporated updates and security fixes to modules and libraries in Altis to bring in important bug fixes
+As always, we continue to incorporate updates to modules and libraries in Altis to bring in essential bug fixes, security patches, 
 and improvements.
 
 ### Documentation