doc: enhance clarification about the main field

removed "this" to enhance sentence flow.

PR-URL: #62302
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: SuperMo0

doc/api/packages.md

@@ -1010,7 +1010,7 @@ added: v0.4.0
 The `"main"` field defines the entry point of a package when imported by name
 via a `node_modules` lookup.  Its value is a path.
 
-When a package has an [`"exports"`][] field, this will take precedence over the
+The [`"exports"`][] field, if it exists, takes precedence over the
 `"main"` field when importing the package by name.
 
 It also defines the script that is used when the [package directory is loaded