docs: clear hexdocs link + type-reference warnings for 0.2.0

- README layout table: examples/README.md and docs/testing.md are now absolute
  GitHub URLs. The relative paths 404 on hexdocs (neither is a doc extra; adding
  docs/testing.md as an extra would cascade its 6 repo-relative links).
- ChunkReader.read_chunk/2 moduledoc: reference read_result as a TYPE
  (t:read_result/0), not a function.

mix docs now emits zero warnings (was 2). Docs-only change; package unchanged.

Author: palermo-git

README.md

@@ -195,8 +195,8 @@ decoding rows into positional tuples of unknown provenance.
 | Directory | Contents |
 | --- | --- |
 | `lib/` | The Elixir library (hex package `capstan`) — the C1 streaming spine |
-| `examples/` | Runnable minimal consumers ([examples/README.md](examples/README.md)) |
-| `docker-compose.yml`, `scripts/` | The local MySQL test substrate ([docs/testing.md](docs/testing.md)) |
+| `examples/` | Runnable minimal consumers ([examples/README.md](https://github.com/baselabs/capstan/blob/main/examples/README.md)) |
+| `docker-compose.yml`, `scripts/` | The local MySQL test substrate ([docs/testing.md](https://github.com/baselabs/capstan/blob/main/docs/testing.md)) |
 | `probe/` | The executed protocol viability probe + committed evidence |
 | `docs/adr/` | Architecture decision records ([0001](docs/adr/0001-position-and-dedup-model.md)–[0005](docs/adr/0005-initial-snapshot-cursor-gate-brief-lock.md)) |
 | `docs/testing.md` | Test environment + how to run the suite |

lib/capstan/snapshot/chunk_reader.ex

@@ -221,7 +221,7 @@ defmodule Capstan.Snapshot.ChunkReader do
   Reads the next chunk of rows with `pk > cursor` (or from the start when `cursor` is `:start`),
   paired with the chunk's exact GTID position `G`, under the pinned brief-lock capture sequence.
 
-  Returns a `#{inspect(__MODULE__)}.read_result/0`. The produced `%Capstan.Snapshot.Chunk{}`
+  Returns a `t:read_result/0`. The produced `%Capstan.Snapshot.Chunk{}`
   carries `g` (the exact lower bound), `rows` (the full row images as `column => value` maps),
   and `max_pk` (the canonical PK of the last row — the value the cursor advances to). Faults are
   classified positionally to `:snapshot_lock_unavailable` / `:snapshot_chunk_read_failed`; a