minor #40180 Fix: Article (localheinz)

This PR was merged into the 4.4 branch.

Discussion
----------

Fix: Article

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | n/a
| License       | MIT
| Doc PR        | n/a

This pull request

* [x] fixes usages of the indefinite article `a` where `an` should be used instead

Commits
-------

34b320ba97 Fix: Article

HeaderUtils.php

@@ -146,7 +146,7 @@ public static function unquote(string $s): string
     }
 
     /**
-     * Generates a HTTP Content-Disposition field-value.
+     * Generates an HTTP Content-Disposition field-value.
      *
      * @param string $disposition      One of "inline" or "attachment"
      * @param string $filename         A unicode string

Request.php

@@ -1716,7 +1716,7 @@ public function getAcceptableContentTypes()
     }
 
     /**
-     * Returns true if the request is a XMLHttpRequest.
+     * Returns true if the request is an XMLHttpRequest.
      *
      * It works if your JavaScript library sets an X-Requested-With HTTP header.
      * It is known to work with common JavaScript frameworks:

Tests/RequestTest.php

@@ -806,7 +806,7 @@ public function getQueryStringNormalizationData()
             ['bar=&foo=bar', 'bar=&foo=bar', '->works with empty parameters'],
             ['foo=bar&bar=', 'bar=&foo=bar', 'sorts keys alphabetically'],
 
-            // GET parameters, that are submitted from a HTML form, encode spaces as "+" by default (as defined in enctype application/x-www-form-urlencoded).
+            // GET parameters, that are submitted from an HTML form, encode spaces as "+" by default (as defined in enctype application/x-www-form-urlencoded).
             // PHP also converts "+" to spaces when filling the global _GET or when using the function parse_str.
             ['baz=Foo%20Baz&bar=Foo+Bar', 'bar=Foo%20Bar&baz=Foo%20Baz', 'normalizes spaces in both encodings "%20" and "+"'],