fix: correctly ignore `class` values in HTML

Signed-off-by: Joseph Kato <joseph@jdkato.io>

vale-cli#1086

chore: fix golangci-lint

Signed-off-by: Joseph Kato <joseph@jdkato.io>

docs: Update DigitalOcean referral information in README

Updated DigitalOcean referral link and badge image.

chore: remove old config

Signed-off-by: Joseph Kato <joseph@jdkato.io>

test: add more cases

Signed-off-by: Joseph Kato <joseph@jdkato.io>

fix: adjust comment offset

Signed-off-by: Joseph Kato <joseph@jdkato.io>

vale-cli#992

fix: don't error on duplicate fields

Signed-off-by: Joseph Kato <joseph@jdkato.io>

chore: add mdx2vast to Docker

refactor: rollback metadata support until next release

WIP

fix: support filters through strings or files

vale-cli#967