chore: organize CHANGELOG for v0.0.3 release (#8)

chore: organize CHANGELOG with v0.0.1, v0.0.2, v0.0.3 version history

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyunhee-jo

CHANGELOG.md

@@ -2,7 +2,33 @@
 
 ## [Unreleased]
 
+## [0.0.3] - 2026-04-14
+
 ### Added
+
+- OpenDataLoaderPDFReaderDemo.ipynb demo notebook (Colab-ready, 44 cells)
+- GitHub issue templates (bug report, feature request, question) and PR template
+- SECURITY.md, CODEOWNERS, .editorconfig
+- Lint CI workflow (ruff + black, enforced on every PR)
+
+### Changed
+
+- Reformatted existing code to pass ruff/black (line-length=100)
+
+### Fixed
+
+- RAG pipeline cell in demo notebook no longer requires HF_TOKEN
+
+## [0.0.2] - 2026-04-10
+
+### Fixed
+
+- Clear error messages for missing input files and unavailable Java runtime
+
+## [0.0.1] - 2026-04-10
+
+### Added
+
 - `OpenDataLoaderPDFReader` with 21 extraction parameters and per-page splitting
 - `SimpleDirectoryReader` `file_extractor` support
 - Hybrid AI extraction mode support (docling-fast backend)