Deprecate other_locations in analyzer spec, to clarify vs. trace

[ches]

It appears that #20 intended to remove other_locations as superseded by trace, but it left the old entry (only) in the example JSON object. An expanded section describing other_locations was put back in #57, that issue thread asserts that it is still valid and in use by Code Climate's duplication engine.

These two fields certainly seem functionally redundant, hence the confusion in #56, which I shared too.

Under assumption that both are used/accepted in implementations of the current version of the spec, this change restores presence of both in the reference but proposes deprecating other_locations and hence de-emphasizes its documentation (Trace objects are already specified in detail).

The spec version was 0.3.1 as of #57, and still is now.