docs: update README

README.md

@@ -1,3 +1,61 @@
----
-license: cdla-sharing-1.0
----
+---
+license: cdla-sharing-1.0
+language:
+  - en
+tags:
+  - music
+  - code
+pretty_name: Spotify Million Song Lyrics Cleaned
+size_categories:
+  - 10K<n<100K
+---
+
+# Spotify Million Song Lyrics Cleaned
+
+CSV of **deduplicated, normalized lyrics** aligned to the Million Song–style raw lyrics dump used in the *viral-content-predictor* project. Each row is one **(artist, song)** identity after normalization; lyrics are cleaned text suitable for TF‑IDF, retrieval, or joining to Spotify metadata via `artist_norm` / `title_norm`.
+
+## File
+
+| File | Role |
+|------|------|
+| `lyrics_cleaned.csv` | One row per normalized `(artist_norm, title_norm)`; includes raw display columns and lyric text. |
+
+## Source
+
+- **Upstream:** Raw lyrics table (e.g. `spotify_millsongdata.csv` in `data/raw/`), derived from the **Spotify Million Song Dataset**–style corpus.
+- **Pipeline:** `notebooks/exploratory/explore_lyrics_clean.ipynb` — normalization, lyric text cleanup, **deduplication** (keeping the longest lyric per normalized artist–title pair where applicable).
+
+## Schema (typical columns)
+
+| Column | Description |
+|--------|-------------|
+| `artist` | Original artist string. |
+| `song` | Original track title string. |
+| `artist_norm` | Normalized artist key for joins. |
+| `title_norm` | Normalized title key for joins. |
+| `lyrics_char_len` | Character length of the lyric text (or similar size signal). |
+| `lyrics` | Full lyric text (cleaned). |
+
+Exact column order and any extra fields follow the exporting notebook revision.
+
+## Usage
+
+```python
+import pandas as pd
+
+lyr = pd.read_csv("lyrics_cleaned.csv")
+# Join to Spotify-side tables on artist_norm / title_norm (and track_id after mapping)
+```
+
+## Size note
+
+The **full** cleaned file can be **large** (multi‑million characters / many rows). If your snapshot is bigger than `10K<n<100K`, update the Hub **`size_categories`** in the YAML (e.g. `1M<n<10M` or `n>10M`) so the dataset card matches reality.
+
+## Limitations
+
+- **Language:** Primarily **English** lyrics in practice; not language-tagged per row in this export.
+- **Rights:** Lyrics are third-party content; redistribution must respect **CDLA-Sharing-1.0** (this card), the original dataset license, and applicable copyright rules in your jurisdiction.
+
+## Citation
+
+Cite the original **Million Song Dataset** / lyrics source you used, plus your repository or notebook revision for the cleaning steps.