<blockquote> it doesn't say anything about 6.1/7 differences</blockquote>
This link shows the difference between the two, hence "What’s new in Safari and WebKit" phrase.

<blockquote> i.e. 537.71, what is your source?</blockquote>
For Safari 6.0 and Safari 7.0 but Safari 7.0.1 is 537.73 and we do not specify the third dot

<blockquote>OK, I'll leave it here then. I still think it'd be good to update it all just before merging and wanted to point out the mistake here but if you insist it can be done later.</blockquote>
First of all we are not leaving it, we will have more in depth discussion about what we should put there, adding another version of Safari is not sufficient and this is not a mistake.