Add a link to ECS

[damienalexandre]

trafficstars

There is a default mapping / suggestion of field name for log data called ECS.

We should add links to some useful documentation about it:

• https://fbaligand.github.io/ecs/
• https://www.elastic.co/guide/en/ecs/current/index.html

[Bhavna777]

I want to work on it.

[damienalexandre]

Great, feel free to open a pull request :+1:

[Bhavna777]

Please assign to me