Enhance Crawl4AI with new features and documentation

- Fix crawler text mode for improved performance; cover missing `srcset` and `data_srcset` attributes in image tags.
  - Introduced Managed Browsers for enhanced crawling experience.
  - Updated documentation for clearer navigation on configuration.
  - Changed 'text_only' to 'text_mode' in configuration and methods.
  - Improved performance and relevance in content filtering strategies.

docs/md_v2/advanced/proxy-security.md

@@ -4,59 +4,67 @@ Configure proxy settings and enhance security features in Crawl4AI for reliable
 
 ## Basic Proxy Setup
 
-Simple proxy configuration:
+Simple proxy configuration with `BrowserConfig`:
 
 ```python
+from crawl4ai.async_configs import BrowserConfig
+
 # Using proxy URL
-async with AsyncWebCrawler(
-    proxy="http://proxy.example.com:8080"
-) as crawler:
+browser_config = BrowserConfig(proxy="http://proxy.example.com:8080")
+async with AsyncWebCrawler(config=browser_config) as crawler:
     result = await crawler.arun(url="https://example.com")
 
 # Using SOCKS proxy
-async with AsyncWebCrawler(
-    proxy="socks5://proxy.example.com:1080"
-) as crawler:
+browser_config = BrowserConfig(proxy="socks5://proxy.example.com:1080")
+async with AsyncWebCrawler(config=browser_config) as crawler:
     result = await crawler.arun(url="https://example.com")
 ```
 
 ## Authenticated Proxy
 
-Use proxy with authentication:
+Use an authenticated proxy with `BrowserConfig`:
 
 ```python
+from crawl4ai.async_configs import BrowserConfig
+
 proxy_config = {
     "server": "http://proxy.example.com:8080",
     "username": "user",
     "password": "pass"
 }
 
-async with AsyncWebCrawler(proxy_config=proxy_config) as crawler:
+browser_config = BrowserConfig(proxy_config=proxy_config)
+async with AsyncWebCrawler(config=browser_config) as crawler:
     result = await crawler.arun(url="https://example.com")
 ```
 
 ## Rotating Proxies
 
-Example using a proxy rotation service:
+Example using a proxy rotation service and updating `BrowserConfig` dynamically:
 
 ```python
+from crawl4ai.async_configs import BrowserConfig
+
 async def get_next_proxy():
     # Your proxy rotation logic here
     return {"server": "http://next.proxy.com:8080"}
 
-async with AsyncWebCrawler() as crawler:
+browser_config = BrowserConfig()
+async with AsyncWebCrawler(config=browser_config) as crawler:
     # Update proxy for each request
     for url in urls:
         proxy = await get_next_proxy()
-        crawler.update_proxy(proxy)
-        result = await crawler.arun(url=url)
+        browser_config.proxy_config = proxy
+        result = await crawler.arun(url=url, config=browser_config)
 ```
 
 ## Custom Headers
 
-Add security-related headers:
+Add security-related headers via `BrowserConfig`:
 
 ```python
+from crawl4ai.async_configs import BrowserConfig
+
 headers = {
     "X-Forwarded-For": "203.0.113.195",
     "Accept-Language": "en-US,en;q=0.9",
@@ -64,21 +72,24 @@ headers = {
     "Pragma": "no-cache"
 }
 
-async with AsyncWebCrawler(headers=headers) as crawler:
+browser_config = BrowserConfig(headers=headers)
+async with AsyncWebCrawler(config=browser_config) as crawler:
     result = await crawler.arun(url="https://example.com")
 ```
 
 ## Combining with Magic Mode
 
-For maximum protection, combine proxy with Magic Mode:
+For maximum protection, combine proxy with Magic Mode via `CrawlerRunConfig` and `BrowserConfig`:
 
 ```python
-async with AsyncWebCrawler(
+from crawl4ai.async_configs import BrowserConfig, CrawlerRunConfig
+
+browser_config = BrowserConfig(
     proxy="http://proxy.example.com:8080",
     headers={"Accept-Language": "en-US"}
-) as crawler:
-    result = await crawler.arun(
-        url="https://example.com",
-        magic=True  # Enable all anti-detection features
-    )
-```
+)
+crawler_config = CrawlerRunConfig(magic=True)  # Enable all anti-detection features
+
+async with AsyncWebCrawler(config=browser_config) as crawler:
+    result = await crawler.arun(url="https://example.com", config=crawler_config)
+```