Add ILM documentation

[albertteoh]

Requirement - what kind of business use case are you trying to solve?

Add documentation relating to this PR: jaegertracing/jaeger#2454

The changes should update the Elasticsearch deployment section, especially to Elasticsearch Rollover: https://www.jaegertracing.io/docs/1.21/deployment/#elasticsearch.

[bhiravabhatla]

@albertteoh - I see an unclosed tag (<1>) at the beginning of few lines in elasticsearch section. Is this expected?

[albertteoh]

Yup, this is expected. It's hard to see but if you scroll across the docker run... command, you'll see a # <1>; which acts as an anchor for the comment. A clearer example of how this is used is here: https://www.jaegertracing.io/docs/1.21/operator/#understanding-custom-resource-definitions

[bhiravabhatla]

Oh okay, I removed them in my PR, let me add them back