📖 governance: Adopt Scorecard project charter

[justaugustus]

What kind of change does this PR introduce?

This PR introduces the Scorecard project charter, which has been approved by @ossf/scorecard-maintainers and adopted on 2024-04-24.

The project charter is included both in markdown and PDF formats.

• PDF: direct export from the finalized charter in Google Docs

• Markdown: exported from the finalized charter in Google Docs --> pandoc conversion to markdown --> manual formatting cleanups from me

• PR title follows the guidelines defined in our pull request documentation

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[spencerschrock]

Do we need the PDF? it's just going to fall out of date in my opinion

[spencerschrock]

LGTM, but seems like something we would want multiple approvals on, so disabled auto-merge.

[justaugustus]

Do we need the PDF? it's just going to fall out of date in my opinion

Discussed with @spencerschrock via DM, but carrying over here for visibility:
PDF provides a simple way for folks that may not be as technically inclined to download or reference the charter.
While this does create some opportunity for drift, the charter should be slow-moving with faster moving changes to happen within operational documentation.

[justaugustus]

LGTM, but seems like something we would want multiple approvals on, so disabled auto-merge.

n.b. the merge of the charter is merely a formality, IMO.
The live document was already approved by us before shipping to LF Legal for execution.

[raghavkaul]

Looks good to merge!