Clarify description for aria-keyshortcuts (#1713)

Fixed the character name and removed the (probably unnecessary) modifier key from an example for `aria-keyshortcuts` - `'` ... `'`, `"` ... `"`

I also removed the Shift modifier, as it's not a part of the escaping sequence and was confusing
(you can type double-quote with shift+single-quote in US keyboard layout).
The combination of modifier keys and escaping sequence exists in the "Examples of valid keyboard shortcuts include" list.

Author: pocka

index.html

@@ -11884,7 +11884,7 @@ <h2>Definitions of States and Properties (all aria-* attributes)</h2>
                                 <p>When implementing keyboard shortcuts authors should consider the keyboards they intend to support to avoid unintended results. Keyboard designs vary significantly based on the device used and the languages supported. For example, many modifier keys are used in conjunction with other keys to create common punctuation symbols, create number characters, swap keyboard sides on bilingual keyboards to switch languages, and perform a number of other functions.</p>
 				<p>For many supported keyboards, authors can prevent conflicts by avoiding keys other than ASCII letters, as number characters and common punctuation often require modifiers. Here, the keyboard shortcut entered does not equate to the key generated. For example, in French keyboard layouts, the number characters are not available until you press the Control key, so a keyboard shortcut defined as "Control+2" would be ambiguous as this is how one would type the "2" character on a French keyboard.</p>
 				<p>If the character used is determined by a modifier key, the author MUST specify the actual key used to generate the character, that is generated by the key, and not the resulting character. This convention enables the assistive technology to accurately convey what keys must be used to generate the shortcut. For example, on most U.S. English keyboards, the percent sign "%" can be input by pressing Shift+5. The correct way to specify this shortcut is "Shift+5". It is incorrect to specify "%" or "Shift+%". However, note that on some international keyboards the percent sign may be an unmodified key, in which case "%" and "Shift+%" could be correct on those keyboards.</p>
-				<p>If the key that needs to be specified is illegal in the host language or would cause a string to be terminated, authors MUST use the string escaping sequence of the host language to specify it. For example, the double-quote character can be encoded as "Shift+&amp;#39;" in HTML.</p>
+				<p>If the key that needs to be specified is illegal in the host language or would cause a string to be terminated, authors MUST use the string escaping sequence of the host language to specify it. For example, the single-quote character can be encoded as "&amp;#39;" in HTML.</p>
 				<p>Examples of valid keyboard shortcuts include:</p>
 				<ul>
 					<li>"A"</li>