Add link to Cost Breakdown Org Dash to Billing Doc

[paolaperaza]

Issue Type

Missing content for an existing feature

Links to Affected Docs

https://www.astronomer.io/docs/astro/manage-billing#view-billing-details

The Issue or Context

From @collinmcnulty -- I think these this page on billing should link to this page on exploring billing breakdowns.

Fix or Proposed Change

Add cross-link

Additional Notes

No response

Required Reviewers

Collin McNulty