Make usage of the verb roll back consistent

Make usage of the verb roll back consistent across the documentation, so it's "roll back" similar to other pages.

Signed-off-by: Andreas Nilsson <[email protected]>

what-needs-work.md

@@ -19,6 +19,6 @@ Broadly there are several areas where we haven’t yet reached our [goals](missi
 This would be confusing to a developer or someone trying to adopt these images.
 The behavior is different from the behavior of containers, where you can make changes to a running container, stop and  start that container without losing those local changes.
 
- * Currently when we deploy a bootable container image to a stock Linux system, without bootc already present, it is not possible to rollback. We should fix this.
+ * Currently when we deploy a bootable container image to a stock Linux system, without bootc already present, it is not possible to roll back. We should fix this.
 
  * Currently the tooling and the base images are limited to using RPM components in the container images. (bootc #468)