Migrate frontmatter og:description to description on non-legacy pages

[GigaHierz]

Follow-up from #2237.

Problem

97% of llms.txt entries have no description. 8 of 264 entries carry one; the rest are bare title + link. An AI assistant reading the index gets titles only, with no signal about what any page covers — which makes it fetch the wrong pages, or too many.

Root cause

Mintlify's llms.txt generator reads only description: and ignores og:description:.

Per Mintlify's SEO reference, og:description sets the OpenGraph tag only and "falls back to description" — it is purely additive and does not set the page meta description.

Confirmed empirically in this repo: home/ramps.mdx has both fields, and its llms.txt entry uses the description: value, not the og:description: one.

So 125 non-legacy pages already have perfectly good description text that is being silently dropped.

Current state

In-nav pages, excluding _deprecated/:

Frontmatter	Count
description:	8
og:description: only	171 (125 non-legacy / 46 legacy)
neither	102 non-legacy

Policy to adopt

• Non-legacy pages → description:
• legacy/** pages → keep og:description:

The legacy split is deliberate, not an oversight: legacy L1 documentation should stay description-less in llms.txt so LLMs don't surface it as current guidance.

This supersedes the previous "always use og:description:" convention, which predated the llms.txt work.

Work

1. The 7 build-on-celo/ pages with no description at all (highest traffic, needs new copy):

   • build-on-celo/quickstart
   • build-on-celo/cel2-architecture
   • build-on-celo/build-with-ai/overview
   • build-on-celo/build-with-ai/x402
   • build-on-celo/build-with-ai/8004
   • build-on-celo/build-with-ai/mpp
   • build-on-celo/build-with-ai/mcp/celo-mcp

2. The 125 non-legacy renames — mechanical og:description: → description:.

3. Remaining zero-description clusters — all 16 specs/*, infra-partners/operators|notices/archive/*, tooling/libraries-sdks/cli/*, tooling/indexers/*, plus home/index, home/history, home/exchanges, home/gas-fees, contribute-to-celo/index.

Minor fix to pick up along the way: build-on-celo/index.mdx has a double space in og:description: A guide for building on Celo.

Verifying

# count entries carrying a description
curl -s https://docs.celo.org/llms.txt | grep -c '\.md): '
# currently 8; should reach ~160 after step 2, ~215 after step 3