fix: stale repo links (ffmpeg-kit -> ffmpeg) + wrong Free artifactId/version Getting-Started.md and FAQ.md referenced the pre-unification artifactId (dev.ffmpegkit-maintained:ffmpeg-kit-free) and an unpublished version (6.0.2, only 6.0.1 is live) -- would break the build for anyone following the tutorial. Also genericized the paid-tier .aar filename example to X.Y.Z (Gumroad keeps multiple versions downloadable, no single exact version to hardcode). 8 stale ffmpeg-kit repo links fixed across 5 pages (GitHub silently 301-redirects the old name, but worth cleaning up).
docs: add GnuTLS/OpenSSL conflict fix to Building page
docs: sync Building page with real android.sh flags and apt deps
docs: populate wiki (Home, FAQ, Compatibility, Building, Migration)