Update publishing-data.rst

Have changed title to reflect importance of data quality - essentially this should be our data quality checklist / hub, no?
I've re-ordered them as 'timely, comprehensive, fwd-looking' was part of the Busan commitment.
Have added 'frequently updated' as there seemed to be reference to that in the 'timely' section - they are different!
Do we want to say something about coverage, given this is a key indicator of data quality for us?
Do we want to say something about data being properly licensed? Or is this a lesser issue?
Line 30 - can we link to the Implementation Schedule page?
Line 48 - should we reference the validator tool that enables people to test their own data?
Lines 51 & 52 - can we get links in to the schema, rulesets etc?
Line 69 - there doesn't appear to be any further info!