[ytdl] add 'deprecations' option

https://github.com/gdl-org/builds/issues/3

docs/configuration.rst

@@ -5824,6 +5824,16 @@ Description
     Location of a |ytdl| configuration file to load options from.
 
 
+extractor.ytdl.deprecations
+---------------------------
+Type
+    ´´bool´´
+Default
+    ``false``
+Description
+    Allow |ytdl| to warn about deprecated options and features.
+
+
 extractor.ytdl.enabled
 ----------------------
 Type
@@ -6351,6 +6361,16 @@ Description
     Location of a |ytdl| configuration file to load options from.
 
 
+downloader.ytdl.deprecations
+----------------------------
+Type
+    ´´bool´´
+Default
+    ``false``
+Description
+    Allow |ytdl| to warn about deprecated options and features.
+
+
 downloader.ytdl.format
 ----------------------
 Type

docs/gallery-dl.conf

@@ -851,6 +851,7 @@
         {
             "cmdline-args": null,
             "config-file" : null,
+            "deprecations": false,
             "enabled"     : false,
             "format"      : null,
             "generic"     : true,
@@ -1068,6 +1069,7 @@
         {
             "cmdline-args"   : null,
             "config-file"    : null,
+            "deprecations"   : false,
             "enabled"        : true,
             "format"         : null,
             "forward-cookies": true,