Hi Wen,

TL-4087 (T-11497) Add ability to upload course/program icons

It was included in the 2.6.0 release.
There is no specific documentation for this functionality however you can find the upload control when logged in as an admin by browsing to Home ▶︎ Site administration ▶︎ Courses ▶︎ Custom icons.

I'll create a ticket now for the documentation team to get this added to the product documentation (TLS-240)

Cheers

Sam