* Create kcl_3x_deep-dive.md
* Update kcl_3x_deep-dive.md
* Update kcl-configurations.md
- Add two KCL configurations - WorkerMetricsTableConfig, CoordinatorStateTableConfig - to let users know how to set the custom table name.
- Update how to set custom names for KCL metadata tables created in DynamoDB
* Added doc for leases and the lease lifecycle.
* Documentation: addressed comments for leases.
+ minor code cleanup
* Documentation: language review.
+ decomposed shard sync UML into two separate diagrams (initialization, loop)
* Documentation: language review touch-ups.
