enh(twig): update keywords list

[MrYamous]

Changes

Update keywords list for Twig according to documentation

Checklist

• Added markup tests, or they don't apply here because it's about updating keywords list
• Updated the changelog at CHANGES.md

[joshgoebel]

I've cleaned up the Twig support a lot in my follow-up commit, any chance you could take a look and provide your thoughts?

[joshgoebel]

Ping.

[MrYamous]

I also noticed Symfony's own twig functions and filters are not in the keywords list for the moment (visible in Symfony's doc and Twig's doc)
Do you think it's too specific or can I add them? Maybe with an other PR

[joshgoebel]

Can one use Twig without Symphony? Def should be a second PR if we go that directly, don't want to slow this one down any further.