doc: remove duplicate 'the' from http2 API doc

PR-URL: #16924
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

doc/api/http2.md

@@ -1781,7 +1781,7 @@ All additional properties on the settings object are ignored.
 ### Using `options.selectPadding`
 
 When `options.paddingStrategy` is equal to
-`http2.constants.PADDING_STRATEGY_CALLBACK`, the the HTTP/2 implementation will
+`http2.constants.PADDING_STRATEGY_CALLBACK`, the HTTP/2 implementation will
 consult the `options.selectPadding` callback function, if provided, to determine
 the specific amount of padding to use per HEADERS and DATA frame.