Create and use a process for wiki backup

[lkatalin]

We should decide and document:

• [ ] How often we will have wiki backups
• [ ] Who should do the backups (automated, probably)
• [ ] Where the backups will be kept
• [ ] How long the backups are kept or how many are kept

Possibly related: enarx/enarx#338

Maybe we should force a backup before any wiki update, if that is possible?

[jackmichalak]

Wikis are git repos with less additional features around them. I confirmed that branch protection rules (i.e. linear history) do not apply to wikis, so I'm presuming the concern is someone modifying the commit history.

I've set up nightly (for me) backups of the enarx.wiki git repo to https://enarx-wiki.us-east-1.linodeobjects.com/ as a backstop. For example, last night's backup is here: https://enarx-wiki.us-east-1.linodeobjects.com/2021-03-14_12-21.tgz

I can commit to keeping them for a month, but anyway I don't have anything set up to remove old backups, and at their current size I'm not incentivized to do so. Shouldn't be difficult to migrate to a different provider if we have an account associated with Enarx instead of me personally. Another option is we could just stuff the backups into a non-wiki repo with linear history enforced.

As for performing a backup with any wiki update, it doesn't seem to me that GitHub Actions can be triggered for wiki repos; most documentation is about going the other direction (updating the wiki in a workflow). I think the closest approximation would be polling to check for updates, but maybe I'm missing something.