* .go files are now tagged with diff=go for better diffs
* go.sum is tagged with generated which suppresses the diff
* go.sum is tagged with merge=ours to reduce merge conflicts
go.mod isn't tagged with generated since it's useful to see it on
dependency bump PRs.
Linguist already classifies vendor/ as vendored files, meaning they
don't count towards things like a repo language stat, but are still
shows in diffs.
By classifying them as generated instead they're not only excluded from
langauge stats but also hidden in diffs.
Daenney