Fix clear rollback confusing text (#568)

* Update README.md

updated a few lines to make more sense

* Update README.md

* Update README.md

cli/README.md

@@ -805,7 +805,7 @@ code-push promote MyApp-iOS Staging Production -t "*"
 
 ## Rolling Back Updates
 
-A deployment's release history is immutable, so you cannot delete or remove an update once it has been released. However, if you release an update that is broken or contains unintended features, it is easy to roll it back using the `rollback` command:
+A deployment's release history is immutable, so you cannot delete or remove individual updates once they have been released without deleting all of the deployment's release history. However, if you release an update that is broken or contains unintended features, it is easy to roll it back using the `rollback` command:
 
 ```
 code-push rollback <appName> <deploymentName>
@@ -859,7 +859,7 @@ By default, the history doesn't display the author of each release, but if you a
 
 ## Clearing Release History
 
-You can clear the release history associated with a deployment using the following command:
+While you can't delete individual releases, you can clear the entire release history associated with a deployment using the following command:
 
 ```
 code-push deployment clear <appName> <deploymentName>
@@ -983,4 +983,4 @@ A: An application running a CodePush SDK that doesn't support code signing will
 
 Q: I've lost my private key, what should I do in this situation?
 
-A: We do not have a copy of your key so you will need to create new private/public key pair, release a new binary update using the new public key, and then release a CodePush update using your new private key.
+A: We do not have a copy of your key so you will need to create new private/public key pair, release a new binary update using the new public key, and then release a CodePush update using your new private key.