add spellchecker, and fix pre-existing issues

[tuminoid]

Add spellchecker to keep our documentation in good shape. Fix pre-existing issues, and add some words to the words list. The base word list is imported from website repository, and then cleaned up from the words not appearing in this repository.

Add shellcheck to lint these hack scripts.

Needs https://github.com/metal3-io/project-infra/pull/625 to merge first. /hold

[tuminoid]

/cc @Rozzii @kashifest @lentzi90

[metal3-io-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kashifest

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/metal3-io/metal3-docs/blob/main/OWNERS)~~ [kashifest] - ~~[design/OWNERS](https://github.com/metal3-io/metal3-docs/blob/main/design/OWNERS)~~ [kashifest] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[metal3-io-bot]

@smoshiur1237: adding LGTM is restricted to approvers and reviewers in OWNERS files.

In response to [this](https://github.com/metal3-io/metal3-docs/pull/379#pullrequestreview-1848622787): >/lgtm Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[tuminoid]

/retest With new checks enabled.

[tuminoid]

/unhold Good to go.