Document how to integrate Chatwoot & Matomo

Closes #828

See merge request exosphere/exosphere!851

Also tried to clarify what Chatwoot is.

Rubric add rank scoring advice and reworded one criterion

See merge request exosphere/exosphere!853

Rename "Criteria" to "Key Factors". This helps to align it with the
terminology used by the paper describing our evaluation strategy. It
also avoids confusion with other uses of the word 'criteria' in the ADR:

1. Criteria for achieving the OpenSSF Best Practices Badge
2. Overall "Success Criteria" as it relates to project health

Updating weekly meeting coordinates to use Jitsi widget in Element room

See merge request exosphere/exosphere!852

Choosing a governance model

Closes #819

See merge request exosphere/exosphere!847

Measurement plan for sustainability metrics

Closes #822

See merge request exosphere/exosphere!850

Allow creation of volume-backed instance when volume quota is unlimited (with refactoring)

Closes #940

See merge request exosphere/exosphere!848

- Added definition of governance
- Make it explicit that we're evaluating joining ASF, OpenInfra, & CNCF
- Merged 'Autonomy & Flexibility' into 'Overhead & Bureaucracy'
- Removed 'N/A' scoring option

Combined where sensible, removed where less important

In anticipation of combining and removing some.

Addressing feedback that "...it is superfluous to all the other
categories (which each look at a dimension of how well the model fits
with the project).

More neutral & objective. Also expanded some points to provide more
context & detail.

Somebody can recommend something if they want.