Fix cds up --to kyma → cds up --to k8s

Can consider offering a `kyma` alias in the future, too late for this release.

Author: swaldmann

get-started/index.md

@@ -241,7 +241,7 @@ Use `cds up` to build and deploy your project in one go:
 ```shell
 cds up
 cds up --to cf
-cds up --to kyma
+cds up --to k8s
 ```
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 cds up --to hana