Interim search suggestion

[JustinDrake]

[The idea was prompted from this Reddit thread. In particular "most buyers are not aware of it's existence"]

Before third party search engines are integrated into OB2.0, it may be helpful for users to know that Duo Search exists when the OpenBazaar search results are empty.

For example, an OpenBazaar search for #coins returns 0 results:

No listings found in your network tagged with #coins

The corresponding query on Duo Search returns 522 results. Would it be helpful for the Duo Search team to submit a pull request where there is a suggestion to use Duo Search? For example:

No listings found in your network tagged with #coins
Have you tried this query on Duo Search?

[jjeffryes]

(ignore the close, hit the wrong button)