Add docs/README.md — reading order and index for all documentation

Start with disc-to-rip.md (the big picture), then architecture,
drive access, disc formats (UDF/MPLS/CLPI), and AACS encryption.

docs/README.md

@@ -0,0 +1,32 @@
+# libfreemkv Documentation
+
+Technical documentation for [libfreemkv](https://github.com/freemkv/libfreemkv), the open source optical drive library.
+
+## Start Here
+
+**[Disc to Rip: End-to-End Flow](disc-to-rip.md)** — How the library goes from a disc in the drive to decrypted content. Read this first.
+
+## Reference
+
+| Document | What it covers |
+|----------|---------------|
+| [Architecture](architecture.md) | Module map, design principles, error codes, platform support |
+| [Drive Access](drive-access.md) | DriveSession, SCSI transport, profiles, unlock, why raw mode is needed |
+| [AACS Encryption](aacs.md) | Key resolution (4 paths), content decryption, bus encryption, SCSI handshake |
+| [UDF Filesystem](udf.md) | UDF 2.50 with metadata partitions, pointer chain, how files are read from disc |
+| [MPLS Playlists](mpls.md) | Playlist format, play items, STN stream table, coding types |
+| [CLPI Clip Info](clpi.md) | EP map (coarse + fine entries), timestamp-to-sector mapping, extent calculation |
+
+## Reading Order
+
+If you want to understand the whole library:
+
+1. **[Disc to Rip](disc-to-rip.md)** — the big picture
+2. **[Architecture](architecture.md)** — how modules fit together
+3. **[Drive Access](drive-access.md)** — how we talk to hardware
+4. **[UDF](udf.md)** → **[MPLS](mpls.md)** → **[CLPI](clpi.md)** — how disc content is structured
+5. **[AACS](aacs.md)** — how encryption works and how we break it
+
+## API Documentation
+
+Generated API docs are on [docs.rs/libfreemkv](https://docs.rs/libfreemkv).