Fix break lines in create helmrelease and source

[hgranillo]

Hello flux maintainers!

This PR fixes a few missing break lines in the create helmrelease and create source help documentation that could lead to some unintended executions if blindly copy-pasted

For example, I've added --export to the create source helm OCI example included in the flux create source helm --help command:

Discovered this while I was pasting examples in my terminal with the --export flag to check if I was using the newest API versions for my flux objects

❯   flux create source helm podinfo \
    --url=oci://ghcr.io/stefanprodan/charts/podinfo
    --username=username \
    --password=password --export
✚ generating HelmRepository source
► applying HelmRepository source
✔ source updated
◎ waiting for HelmRepository source reconciliation
^C

[stefanprodan]

LGTM

Thanks @hgranillo