Add introduction text with example on how to use

[belvederef]

Anonymous feedback:

Some examples would be really useful. What can I search for?|2020-05-07 11:06:58

Johnny's comment:

I've used it when I know there's a certain property I want to assign to an entity and want to reuse it if it already exists (for example, I want concepts in STRVCT to have "keywords", and figured that already existed so I used pronto and just searched for the "keywords" predicate