Assuming (path) is a physical directory on your machine, create a new web.config file in that directory with the following content:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<staticContent>
<mimeMap fileExtension="." mimeType="text/xml" />
</staticContent>
</system.webServer>
</configuration>
You are telling IIS that for this directory only, any file without an otherwise defined extension (in MIME types) should be considered an xml file. Other file types in the same path should still work.
If you have the Windows feature IIS Management Scripts and Tools
installed, you can use PowerShell to create such a web.config file:
Add-WebConfigurationProperty -pspath 'MACHINE/WEBROOT/APPHOST/Default Web Site/.well-known' -filter "system.webServer/staticContent" -name "." -value @{fileExtension='.';mimeType='text/xml'}
in this example Default Web Site
is the name of the web site and .well-known
is a directory under that site.