docs: short README (structure overview + file-map)

README.md

@@ -0,0 +1,24 @@
+---
+license: other
+language:
+- en
+tags:
+- itu
+- itu-t
+- telecom
+- standards
+---
+
+# ITU-T source mirror
+
+This dataset mirrors the ITU Telecommunication Standardization Sector (ITU-T) Recommendations. Every source is kept twice: `original/` is the Recommendation as ITU-T released it (PDF), and `marked/` is that same document converted to Markdown for search and retrieval, one `raw.md` per document with any figures extracted beside it. The two trees share identical paths, so a file in `original/` has a parsed twin at the matching path under `marked/`; both are grouped by ITU-T Recommendation series, the single-letter folders A through Z. `manifest.jsonl` carries one row per file (path, SHA-256, parse status), and `STATUS.md` reports how much of the corpus has been parsed.
+
+```text
+itu/
+  original/         # Recommendations as published, by series
+    G/  H/  Q/  Y/  ...
+  marked/           # Markdown mirror of original/, same paths
+    Y/.../raw.md    #   one per document, images beside it
+  manifest.jsonl    # one row per file: path, sha256, parse status
+  STATUS.md         # parse-coverage summary
+```