Add README with schema documentation

README.md

@@ -0,0 +1,63 @@
+---
+license: other
+tags:
+  - mortgage
+  - fannie-mae
+  - ami
+  - income-limits
+  - homeready
+  - county
+---
+
+# Fannie Mae 2026 County-Level AMI Data
+
+Official 2026 Area Median Income (AMI) data from Fannie Mae for all 3,144 US counties.
+Used for HomeReady® and Home Possible® income eligibility checks.
+
+## Files
+
+| File | Description |
+|---|---|
+| `fannie-ami-2026-county.json` | Key-value lookup by 5-digit county FIPS code |
+| `fannie-ami-2026.jsonl` | JSONL format, one record per county |
+| `fannie-ami-2026-by-state.json` | Organized by state name |
+
+## Schema
+
+Each record contains:
+- `fips` — 5-digit county FIPS code (e.g., `"28035"`)
+- `county` — County name
+- `state` — State name
+- `highCostArea` — Boolean, true if designated high-cost area
+- `ami` — 2026 Area Median Income
+- `veryLowIncome` — 50% AMI (very low-income threshold)
+- `lowIncome` — 80% AMI (low-income threshold)
+- `homeReadyLimit` — HomeReady® borrower income eligibility limit (= HP Borrower's Income Eligibility from Fannie Mae)
+- `ami2025` — 2025 AMI for year-over-year comparison
+- `amiChange` — Dollar change from 2025 to 2026
+- `totalTracts` — Number of census tracts in county
+
+## Usage
+
+```javascript
+// Fetch county AMI data
+const res = await fetch(
+  'https://huggingface.co/datasets/Good-News-Lending/fannie-ami-2026/resolve/main/fannie-ami-2026-county.json'
+);
+const amiData = await res.json();
+
+// Look up by 5-digit FIPS
+const forrestCountyMS = amiData['28035'];
+// { fips: '28035', county: 'Forrest', state: 'Mississippi', ami: 79800, homeReadyLimit: 63840, ... }
+```
+
+## Source
+
+Fannie Mae 2026 MFI/AMI County Data  
+Published: 2026  
+Source: [Fannie Mae AMI Lookup Tool](https://ami-lookup-tool.fanniemae.com/amilookuptool/)
+
+## Maintained By
+
+[Good News Lending](https://www.goodnewslending.com)  
+Beau Thompson, NMLS #1615561 | Tate Thompson, NMLS #2473962