[Feature Request] Add a notice in the source when there is no canonical URL tag due to noindex'ing.

[rmarcano]

We've received a request from a user to include a notice in the source of the page viewable to admins only, stating that there is no canonical URL because the page is noindex'ed.

This might save some time for confused admins looking for the reason why there is no canonical URL tag.

This notice could be similar to the one currently shown to admins when there is no meta description specified:

The user has a code suggestion in the conversation number specified below.

[rmarcano]

Please inform the customer of conversation # 335870 when this conversation has been closed.

[jonoalderson]

This is smart - we should do this.

[Pcosta88]

Please inform the customer of conversation # 388266 when this conversation has been closed.

[rmarcano]

Please inform the customer of conversation # 631394when this conversation has been closed.

[pattonwebz]

Is there some way that I can push this forward? Seeing this notice would have saved me some time earlier today.

Additionally having an easy way to selectively override this no canonical if noindex behavior would be good too - but I will find or make a different issue about that.