Update website/content/docs/upgrading/upgrade-to-0.7.0.mdx

Co-authored-by: Loann Le <84412881+taoism4504@users.noreply.github.com>

website/content/docs/upgrading/upgrade-to-0.7.0.mdx

@@ -13,7 +13,7 @@ for Vault 0.7.0 compared to the most recent release. Please read it carefully.
 
 ## Rename of `backend` config key to `storage`
 
-When configuring Vault, the `backend` key that previously was used to configure
+When configuring Vault, the `backend` key previously used to configure
 storage has now been renamed to `storage`. Vault will alias the old key to the
 new path, though users are encouraged to update their configuration to ensure
 minimal disruption in the future when the alias is removed.