add additional comments

Author: Mantisus

docs/guides/code_examples/http_crawlers/selectolax_context.py

@@ -6,6 +6,8 @@
 from crawlee.crawlers._abstract_http import ParsedHttpCrawlingContext
 
 
+# Custom context for Selectolax parser, you can add your own methods here
+# to facilitate working with the parsed document.
 @dataclass(frozen=True)
 class SelectolaxLexborContext(ParsedHttpCrawlingContext[LexborHTMLParser]):
     """Crawling context providing access to the parsed page.

docs/guides/code_examples/http_crawlers/selectolax_crawler.py

@@ -17,6 +17,9 @@
     from crawlee.crawlers._abstract_http import ParsedHttpCrawlingContext
 
 
+# Custom crawler using custom context, It is optional and you can use
+# AbstractHttpCrawler directly with SelectolaxLexborParser if you don't need
+# any custom context methods.
 class SelectolaxLexborCrawler(
     AbstractHttpCrawler[SelectolaxLexborContext, LexborHTMLParser, LexborNode]
 ):
@@ -30,6 +33,8 @@ def __init__(
         async def final_step(
             context: ParsedHttpCrawlingContext[LexborHTMLParser],
         ) -> AsyncGenerator[SelectolaxLexborContext, None]:
+            # Yield custom context wrapping with additional functionality around the base
+            # context.
             yield SelectolaxLexborContext.from_parsed_http_crawling_context(context)
 
         # Build context pipeline: HTTP request -> parsing -> custom context.