Migrate api.stackstorm.com to GH static pages

[arm4b]

Currently, https://api.stackstorm.com/ docs are deployed to AWS S3 on every build.
Migrating to native GH static pages unties docs from AWS and would improve the transparency via git, security, and maintenance.
We had a good experience with Github Static pages as a great alternative so far where additional infra would be redundant.

Depends on #15

Relevant story for st2docs: StackStorm/st2docs#1096

[arm4b]

@bishopbm1 Looks like that's the task for Encore per Slack https://stackstorm-community.slack.com/archives/C020U70RZRR/p1646333439674819.
Happy to answer any questions or give pointers on this one.