Add thin dataset card (ADR-0005)

README.md

@@ -0,0 +1,32 @@
+---
+license: cc-by-4.0
+pretty_name: PetroDB
+tags:
+  - petroleum
+  - reservoir-engineering
+  - parquet
+  - duckdb
+---
+
+# PetroDB
+
+Public petroleum datasets served as a partitioned **parquet** tree, designed for
+remote columnar queries with DuckDB `httpfs` (HTTP Range pushdown).
+
+This Hugging Face dataset repo hosts the **parquet bytes only**. It mirrors the
+`parquet/` root and is queried directly via `resolve` URLs, which honour HTTP
+Range requests so consumers fetch only the row groups a predicate needs.
+
+```sql
+INSTALL httpfs; LOAD httpfs;
+SELECT *
+FROM 'https://huggingface.co/datasets/sumpalabs/petrodb/resolve/main/<dataset>/...';
+```
+
+The human-facing landing page, per-dataset schema docs, and discovery manifests
+live at **https://petrodb.ocortez.com**.
+
+- `main` — public production deployment
+- `stage` — pre-production validation branch
+
+See ADR-0005 in the project repository for the hosting rationale.