Update Sidekiq integration docs (#12598)
Update Sidekiq integration docs (#12598)

* Update Sidekiq integration docs

This PR adds info about an alternative option to configure dogstatsd mapper profiles with the DD_DOGSTATSD_MAPPER_PROFILES environment variable. A 
 few customers have reached out about not understanding how to add these configs to containerized environments (https://datadog.zendesk.com/agent/tickets/801720). This should hopefully cut down on confusion in setting these parameters without directly editing the datadog.yaml file.

* Update sidekiq/README.md

Co-authored-by: cecilia saixue watt <68dd74d5464d42706afe3175604ae6dd0529cacd@datadoghq.com>
DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core