Documentation: Adding Compute Gateway FFCF Split Handling to Engineer Documentation

[philipthomas-MSFT]

Is your feature request related to a problem? Please describe.
No problems, since Compute Gateway uses .NET SDK, just more documentation to help transfer knowledge, have more visibility into the inner workings of FFCF from Compute Gateway, and for troubleshooting issues.

Describe the solution you'd like
An additional folder for Compute Gateway in the Cosmos DB engineering docs.

SDK and client libraries/
│
├── Compute Gateway/
│   ├── main/
│       ├── All Versions and Deletes/
│          └── ./all-versions-and-deletes/split-handling.md
│             ├── support/
│               └── ./all-versions-and-deletes/support/main.md
│          └── ./all-versions-and-deletes/archival-tree-caching.md
│             ├── support/
│               └── ./all-versions-and-deletes/support/main.md

Change needs to be made to sdk/toc.yml.

Describe alternatives you've considered
TBD

Additional context
In scope will be establishing folder structure and touch on Configurations for opting into FFCF split handling, and KUSTO logs for determining if account is enabled, and if the Archival Tree Caching creating and evicting properly.