[YoutubeDL] Improve extract_info doc (#28946)

Co-authored-by: Sergey M. <dstftw@gmail.com>

youtube_dl/YoutubeDL.py

@@ -773,11 +773,20 @@ class YoutubeDL(object):
 
     def extract_info(self, url, download=True, ie_key=None, extra_info={},
                      process=True, force_generic_extractor=False):
-        '''
-        Returns a list with a dictionary for each video we find.
-        If 'download', also downloads the videos.
-        extra_info is a dict containing the extra values to add to each result
-        '''
+        """
+        Return a list with a dictionary for each video extracted.
+
+        Arguments:
+        url -- URL to extract
+
+        Keyword arguments:
+        download -- whether to download videos during extraction
+        ie_key -- extractor key hint
+        extra_info -- dictionary containing the extra values to add to each result
+        process -- whether to resolve all unresolved references (URLs, playlist items),
+            must be True for download to work.
+        force_generic_extractor -- force using the generic extractor
+        """
 
         if not ie_key and force_generic_extractor:
             ie_key = 'Generic'