Uploaded files can be indexed by search engines

[maxwiseman]

Summary:

When a teacher uploads a file, Canvas creates a Canvadoc session so that students can view it. It seems some of these are being indexed by search engines, although they probably shouldn't be.

Steps to reproduce:

Take a look at this Google search

Expected behavior:

These files should either not be indexed, or Canvas should give teachers a warning that they will be indexed

Actual behavior:

These files are indexed