SEO follow-ups: external verifications, topics, backlinks, cross-links

[ringof]

Follow-up tracking for the SEO discoverability work merged in #10. These
items live outside the repo (GitHub UI, Google/Bing consoles, sibling
repos) or require inputs we don't yet have, so they couldn't ship with
the PR itself.

Manual / external (do these soon)

• Repo Topics — add to the About sidebar (you confirmed all four clusters):
  • rx888, rx888-mk2
  • gnuradio, gnuradio-oot, sdr
  • fx3, cypress-fx3, usb3
  • hf, shortwave, direct-sampling, adc, firmware
• Repo About → Website field set to https://ringof.github.io/gr-rx888/
• Bing Webmaster Tools — site is verified via the msvalidate.01 meta tag now on the docs page. Once Pages has rebuilt: click Verify, then submit https://ringof.github.io/gr-rx888/sitemap.xml.
• Google Search Console — apex verification (ringof.github.io) handled outside this repo. After verifying the apex, submit https://ringof.github.io/gr-rx888/sitemap.xml from inside Search Console.
• Sanity check link previews — paste https://ringof.github.io/gr-rx888/ into Mastodon/Slack/Discord, confirm the new title + description render.

Backlinks (highest leverage — playbook §4.2)

• ringof/rx888-tools README/wiki — add a "See also: gr-rx888 (GNU Radio integration)" link. You own that repo; free high-authority backlink.
• Cross-link between sibling project sites (playbook §4.3) — once the other two project URLs are nailed down, add a "Related projects" / "See also" block to each of:
  • docs/index.html in this repo
  • the two sibling project sites
  • the ringof.github.io apex page (which can link all three)
• One on-topic external backlink — choose one of:
  • RX-888 / ka9q-radio mailing list post
  • r/RTLSDR or r/amateurradio post
  • EEVblog SDR thread
  • hackaday.io project page
  • Personal blog post

Optional follow-ups (do anytime)

• Open Graph image — drop a 1200×630 PNG at docs/assets/og-image.png (a screenshot of the AM BCB waterfall demo would work well), then wire up og:image and twitter:image tags in docs/index.html. Modest SEO impact; meaningful sharing impact.
• Project-scoped Google verification (optional, in addition to the apex one) — if you want Search Console data filtered to just /gr-rx888/, create a URL-prefix property at https://ringof.github.io/gr-rx888/, grab the meta-tag token, and we can add a second google-site-verification tag to docs/index.html.

Tier 3 — defer until we have data

After ~1 month of indexing, check Search Console's Coverage + Performance
reports. If you're not surfacing for the core queries, this is when the
deeper content work becomes worth doing:

• Rewrite docs/index.html H2 headings as literal search-query phrases (playbook §3.2)
• Add an "If you're about to write <X>, here's what's already done" landing section (playbook §3.4)
• Audit each page's first ~50 words for keyword coverage (playbook §3.1)

References

• Playbook used: Jekyll on GitHub Pages — SEO Playbook for Small Project Sites
• Implementation PR: seo: low-risk discoverability pass on docs/ and README #10