Investigate whether onDownloadProgress works [skynet-js]

[MSevey]

It may only work for methods that create a request, such as getFileContent.

Update docs to reflect this

[parajbs]

Hello MSevey,

When I last looked at the code of "skynet-js" to port the functions "onDownloadProgress" and "onUploadProgress" to "nodejs-skynet", I noticed that it is not integrated for "downloadFile", since only a "window.location.assign(url)" is executed.

In "nodejs-skynet" "axios" is used for the "downloadFile" function.
I got it running there, but only in my version, since you didn't want the changes.