Change "Get help with this panel" download button from "Dashboard" to "Panel"

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: For clarity on what is actually be downloaded to be shared  **What would you like to be added**: Sometimes I don't want to hand over the whole dashboard and data but am ok handing over the panel. This button only downloads the panel, but reads like the whole dashboard will be downloaded, which might cause some to avoid it. **Who is this feature for?** Anyone who might share dashboard panels for debugging.