Generate an eldoc string for a datomic query.

Generate an eldoc from `info`.

The result is a map featuring:

* :ns or :class - depending on whether we're dealing with Clojure or Java symbol
* :name or :member - depending on whether we're dealing with Clojure or Java symbol
* :eldoc - a list of type signatures suitable to be displayed by Emacs's eldoc
* :type - the type of the symbol (e.g. function, variable, special-form)
* :docstring

See `orchard.info/info` for the structure of the `info`.