Release minor change to hospital-admissions smoothing

[krivard]

• Link to PR
• Proposed release version: whatever's easy

While shifting hospital-admissions over from left-gauss-linear to savgol@1 results in changes on the order of <0.1%, it does affect a thresholding step, and a handful of regions on some dates get added or removed due to the change. These effects should be documented and announced.

• draft and review changes to API documentation
• draft and review API mailing list notification