draft: OTA Firmware Updates for Matter Devices via nRF Cloud (#629)

- [x] Fix trailing comma in YAML front matter description (`OTA
backend,` → `OTA backend.`)
- [x] Fix mixed reference-link/footnote syntax (`[Memfault OTA
documentation][^memfault_ota]` → `Memfault OTA
documentation[^memfault_ota]`)

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: franc0is <4192460+franc0is@users.noreply.github.com>

Author: 3 people