[Documentation]: Cross Reference the User Guide from the Spec

[damianmoz]

Many areas of the spec are (somewhat) understandably devoid of examples.

A judicious cross reference to the user guide from within the spec would be often useful.

For example, within Array Promotion of User Functions, in a search for an example, one follows the cross reference
to Promotion within the spec. Still no clear example. Very frustrating. What was really needed was a cross reference to something like Promotion: implicit data parallelism — Chapel Documentation 2.3. Far more enlightening.

Just a thought.