README roadmap, GOOD_FIRST_ISSUES.md and CHANGELOG are out of date

[adaumsilva]

Description

Several docs still describe the v0.1.0 state:

• README.md Roadmap table marks PDF loader, HuggingFace embedder, FAISS, ChromaDB, recursive chunker and Jupyter notebook as Open — all six are merged (issues PDF Document Loader #1, Recursive / Semantic Text Chunker #3, FAISS Vector Store Retriever #4, ChromaDB Retriever Integration #5, HuggingFace Sentence Transformers Embedder #7, Jupyter Notebook Example & Getting-Started Guide #10 closed)
• .github/GOOD_FIRST_ISSUES.md says issues "will be opened" and lists the same six finished items as available work; it also duplicates the content of .github/issues/*.md, so it drifts every time an issue file changes
• CHANGELOG.md [Unreleased] section: missing blank line before ## [0.1.0], and two entries lack backticks (RecursiveChunker, PDFLoader) unlike the others
• examples/README.md says OpenAI integrations "are not included" — still true, but it should point at the open issues (OpenAI Embeddings Integration #6, OpenAI LLM Generator #8, Anthropic LLM Generator Integration #20) instead of the stale good-first-issues file
• Ten source docstrings reference .github/GOOD_FIRST_ISSUES.md (e.g. InMemoryRetriever, EchoGenerator, RandomEmbedder, loaders.py, chunkers.py) — they should link to the GitHub issues page instead so they don't rot

Acceptance criteria

• Roadmap table reflects reality (Done / Open / In progress) and links each row to its issue number
• GOOD_FIRST_ISSUES.md becomes a short pointer: how to find issues (label:"good first issue" link), how to claim one, link to CONTRIBUTING.md. Detailed specs live only in .github/issues/*.md + GitHub
• CHANGELOG.md formatting fixed
• Docstring references updated to https://github.com/adaumsilva/RAG-framework/issues
• examples/README.md links to the open integration issues

Files to touch

• README.md
• .github/GOOD_FIRST_ISSUES.md
• CHANGELOG.md
• examples/README.md
• ragframework/document/loaders.py, ragframework/document/chunkers.py, ragframework/embeddings/random_embedder.py, ragframework/retriever/in_memory.py, ragframework/generator/echo_generator.py

Estimated effort: Small (< 2 hours)