Add Codebundles for handling Laggy Patroni Replicas

[jon-funk]

• Adds an SLI for fetching the maximum lag (in MB) among replicas in a Patroni cluster within a Kubernetes cluster
• Adds a taskset which can automatically remediate laggy replicas by reinitializating them using patronictl from a Kubernetes workload

[stewartshea]

@jon-funk Just those updates to the readme and then we can push it through. FWIW, I know it's a bit nitpicky, but since those use cases show up on the index, they likely have too much text to fit into a smaller field.

[jon-funk]

@stewartshea updated the doc strings