Ensure guides and tutorials cache against their canonical name

[gregturn]

Whenever we rename a guide or tutorial's repository, github inserts a redirect. This allows old links to continue serving new content.

The risk is that an old cached copy from the legacy name could hang around and NOT get cleaned out when newer commits and pushed on the new repository, like this => https://www.textcompare.org/index.html?id=5ecebd1b1f9d610017e30d55

If you could ensure caching is done against the canonical name of a tutorial or a guide, this may solve the problem of stale caches.

[UgmaDevelopment]

For a suspected example of this, see spring-guides/tut-rest#93.