use yt-dlp by default (#1850, #2028)

docs/configuration.rst

@@ -2275,10 +2275,13 @@ extractor.ytdl.module
 Type
     ``string``
 Default
-    ``"youtube_dl"``
+    ``null``
 Description
     Name of the youtube-dl Python module to import.
 
+    Setting this to ``null`` will try to import ``"yt_dlp"``
+    followed by ``"youtube_dl"`` as fallback.
+
 
 extractor.ytdl.raw-options
 --------------------------
@@ -2564,10 +2567,13 @@ downloader.ytdl.module
 Type
     ``string``
 Default
-    ``"youtube_dl"``
+    ``null``
 Description
     Name of the youtube-dl Python module to import.
 
+    Setting this to ``null`` will first try to import ``"yt_dlp"``
+    and use ``"youtube_dl"`` as fallback.
+
 
 downloader.ytdl.outtmpl
 -----------------------

docs/gallery-dl.conf

@@ -303,7 +303,7 @@
             "format": null,
             "generic": true,
             "logging": true,
-            "module": "youtube_dl",
+            "module": null,
             "raw-options": null
         },
         "booru":
@@ -337,7 +337,7 @@
             "format": null,
             "forward-cookies": false,
             "logging": true,
-            "module": "youtube_dl",
+            "module": null,
             "outtmpl": null,
             "raw-options": null
         }