feat(markdown): add content source selection for markdown generation

Adds a new content_source parameter to MarkdownGenerationStrategy that allows
selecting which HTML content to use for markdown generation:
- cleaned_html (default): uses post-processed HTML
- raw_html: uses original webpage HTML
- fit_html: uses preprocessed HTML for schema extraction

Changes include:
- Added content_source parameter to MarkdownGenerationStrategy
- Updated AsyncWebCrawler to handle HTML source selection
- Added examples and tests for the new feature
- Updated documentation with new parameter details

BREAKING CHANGE: Renamed cleaned_html parameter to input_html in generate_markdown()
method signature to better reflect its generalized purpose

docs/examples/markdown/content_source_short_example.py

@@ -0,0 +1,42 @@
+"""
+Example demonstrating how to use the content_source parameter in MarkdownGenerationStrategy
+"""
+
+import asyncio
+from crawl4ai import AsyncWebCrawler, CrawlerRunConfig, DefaultMarkdownGenerator
+
+async def demo_markdown_source_config():
+    print("\n=== Demo: Configuring Markdown Source ===")
+
+    # Example 1: Generate markdown from cleaned HTML (default behavior)
+    cleaned_md_generator = DefaultMarkdownGenerator(content_source="cleaned_html")
+    config_cleaned = CrawlerRunConfig(markdown_generator=cleaned_md_generator)
+
+    async with AsyncWebCrawler() as crawler:
+        result_cleaned = await crawler.arun(url="https://example.com", config=config_cleaned)
+        print("Markdown from Cleaned HTML (default):")
+        print(f"  Length: {len(result_cleaned.markdown.raw_markdown)}")
+        print(f"  Start: {result_cleaned.markdown.raw_markdown[:100]}...")
+
+    # Example 2: Generate markdown directly from raw HTML
+    raw_md_generator = DefaultMarkdownGenerator(content_source="raw_html")
+    config_raw = CrawlerRunConfig(markdown_generator=raw_md_generator)
+
+    async with AsyncWebCrawler() as crawler:
+        result_raw = await crawler.arun(url="https://example.com", config=config_raw)
+        print("\nMarkdown from Raw HTML:")
+        print(f"  Length: {len(result_raw.markdown.raw_markdown)}")
+        print(f"  Start: {result_raw.markdown.raw_markdown[:100]}...")
+
+    # Example 3: Generate markdown from preprocessed 'fit' HTML
+    fit_md_generator = DefaultMarkdownGenerator(content_source="fit_html")
+    config_fit = CrawlerRunConfig(markdown_generator=fit_md_generator)
+
+    async with AsyncWebCrawler() as crawler:
+        result_fit = await crawler.arun(url="https://example.com", config=config_fit)
+        print("\nMarkdown from Fit HTML:")
+        print(f"  Length: {len(result_fit.markdown.raw_markdown)}")
+        print(f"  Start: {result_fit.markdown.raw_markdown[:100]}...")
+
+if __name__ == "__main__":
+    asyncio.run(demo_markdown_source_config())