Invalid link to data_conventions.md

[holmes1412]

Background

data_conventions.md is invalid.

Problem

In the following document,
https://github.com/opentracing/specification/blob/master/specification.md#the-big-picture-opentracings-scope ,
the link to data modelling conventions, while indicates https://github.com/opentracing/specification/blob/master/data_conventions.md
is 404 NOT FOUND.

Proposal

I found data conventions in commit log. I guess maybe now it`s part of the semantic_conventions.md ?

Questions to address

It would be appreciated if the invalid link could be fixed~

[yurishkuro]

Thanks for reporting.