Clarify MIME-Type Usage

[shartte]

Currently the MIME-Types for the different MSIX file types are only mentioned on the setup page for IIS/Azure Web Sites. It should be clarified whether these MIME-Types are:
a) Required for AppInstaller to work, or if application/octet-stream is sufficient
b) Are intended to be official or not.

If they are intended to be "official", it'd be helpful to have a primary source that specifies these Mime-Types rather than just having them mentioned in the setup guides for specific web hosting technologies.
This came up as part of me trying to add these MIME-Types to the mime-db that Github uses (for example):
jshttp/mime-db#181

[rgwood]

@KevinLaMS It'd be awesome if this could get some attention.

The current experience of hosting .appinstaller and .msix files on services like S3 is painful because they often don't get the MIME types right (and then App Installer breaks). Official documentation for the required MIME types (or even just a "yes, these are required+official" message in this issue) would be a good step toward improving this.

[RDMacLachlan]

An update has been made to the Docs articles. Changes are pending review...

[riverar]

The documentation should also reflect required HTTP server features (HEAD method with non-zero content length, ETags, range requests).

[RDMacLachlan]

Hi @riverar, I'll see what I can do to update the documentation based on the inquiries in the linked GitHub issue.