README: main mirrors the latest release; add dataset viewer configs

Claude-Session: https://claude.ai/code/session_019jhbPVKzWGSubG2HoKReUR

README.md

@@ -10,6 +10,19 @@ tags:
   - anomalies
 size_categories:
   - 100M<n<1B
+# dataset viewer tables (files on main, which mirrors the latest release)
+configs:
+  - config_name: long_short_returns
+    data_files: "Portfolios/Full Sets OP/PredictorLSretWide.parquet"
+    default: true
+  - config_name: predictor_portfolios
+    data_files: "Portfolios/Full Sets OP/PredictorPortsFull.parquet"
+  - config_name: placebo_portfolios
+    data_files: "Portfolios/Full Sets OP/PlaceboPortsFull.parquet"
+  - config_name: signal_doc
+    data_files: "SignalDoc.parquet"
+  - config_name: predictors
+    data_files: "Firm Level Characteristics/Predictors.parquet"
 ---
 
 # Open Source Cross-Sectional Asset Pricing (data releases)
@@ -20,8 +33,9 @@ produced by the code at [github.com/OpenSourceAP/CrossSection](https://github.co
 The official data page and FAQ are at [openassetpricing.com](https://www.openassetpricing.com), which
 includes a [browser for signal descriptions](https://openassetpricing.com/SignalDoc-Browser.html).
 
-**Each data release is its own branch of this repo.** The `main` branch holds only this
-README. The latest release is on branch `Data-Release-2026.10`.
+**Each data release is its own branch of this repo.** The latest release is on branch
+`Data-Release-2026.10`, and the `main` branch holds a copy of it (plus this README), so
+downloads without `revision=` get the latest data.
 
 The data are licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). If you
 use them, please cite [Chen and Zimmermann (2022)](#citation).