doc: simple doc typo fix

decipher.setAuthPadding canged to decipher.setAutoPadding

PR-URL: https://github.com/nodejs/node/pull/6041
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Klauke <romaaan.git@gmail.com>

doc/api/crypto.markdown

@@ -286,7 +286,7 @@ cipher text should be discarded due to failed authentication.
 ### decipher.setAutoPadding(auto_padding=true)
 
 When data has been encrypted without standard block padding, calling
-`decipher.setAuthPadding(false)` will disable automatic padding to prevent
+`decipher.setAutoPadding(false)` will disable automatic padding to prevent
 [`decipher.final()`][] from checking for and removing padding.
 
 Turning auto padding off will only work if the input data's length is a