doc: do not identify string as "JavaScript string"

A parameter that is explicitly identified as a string does not need to
be further specified in the text as a "JavaScript string". Remove the
type altogether as it is indicated in the argument description.

PR-URL: #19689
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

doc/api/buffer.md

@@ -461,8 +461,8 @@ changes:
 * `string` {string} String to encode.
 * `encoding` {string} The encoding of `string`. **Default:** `'utf8'`
 
-Creates a new `Buffer` containing the given JavaScript string `string`. If
-provided, the `encoding` parameter identifies the character encoding of `string`.
+Creates a new `Buffer` containing `string`. If provided, the `encoding`
+parameter identifies the character encoding of `string`.
 
 ```js
 const buf1 = new Buffer('this is a tést');
@@ -839,8 +839,8 @@ added: v5.10.0
 * `string` {string} A string to encode.
 * `encoding` {string} The encoding of `string`. **Default:** `'utf8'`
 
-Creates a new `Buffer` containing the given JavaScript string `string`. If
-provided, the `encoding` parameter identifies the character encoding of `string`.
+Creates a new `Buffer` containing `string`. If provided, the `encoding`
+parameter identifies the character encoding of `string`.
 
 ```js
 const buf1 = Buffer.from('this is a tést');