docs: Add LICENSE file with copyright notice link

[jdbaldry]

Adds a LICENSE file to docs/sources directory with a link to the copyright notice.

[jdbaldry]

I actually want to put this in /docs/ not /docs/sources/

[yesoreyeram]

@jdbaldry - What's the purpose of this? and why this is different from https://github.com/grafana/grafana-json-datasource/blob/main/LICENSE

[jdbaldry]

I believe our docs are subject to a separate licensing as described in https://grafana.com/docs/copyright-notice/.

[yesoreyeram]

make sens. But this licensing refers to documentation or the plugin itself? If plugin iteself, then https://github.com/grafana/grafana-json-datasource/blob/main/LICENSE will make more sense I belive.

Anyhow, you closed this PR for some reason. So feel free to ignore my comments 😄

[yesoreyeram]

I see this is documentation copyright. makes sense now. :)

[jdbaldry]

Cool, I'm make the follow up PR more clear about the intent and before I open it I'm checking with the GOSSIP team if it's even necessary :)

[yesoreyeram]

BTW, FYI. plugin licensing is available in the plugins catalog https://grafana.com/grafana/plugins/marcusolsson-csv-datasource/
and also referred in other places such as https://ops.grafana-ops.net/plugins/marcusolsson-csv-datasource