doc: erase unneeded eslint-plugin-markdown comment

eslint-plugin-markdown comments affect only a code block below them,
so there is no need to cancel them for the rest code blocks.

PR-URL: https://github.com/nodejs/node/pull/14598
Refs:
 https://github.com/eslint/eslint-plugin-markdown#configuration-comments
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/console.md

@@ -235,7 +235,6 @@ abc: 1
 undefined
 >
 ```
-<!-- eslint-enable -->
 
 ### console.dir(obj[, options])
 <!-- YAML