Design re-indexing strategy as policies change

[scotwells]

Summary

We need to update our indexing design to handle re-indexing resources after a policy is changed. The index should be re-built in the background as new documents are processed.

We should ensure that re-indexing will restart where it left off if the service was to restart.

Acceptance Criteria

• Document updated with design proposal on how to handle re-indexing when policies are updated

[JoseSzycho]

Note

Also include logic for indexing existing resources when a new ResourceIndexPolicy is created