VoiceOver reads Tab elements as "Tab Description" (facebook#30689)

Summary:
On iOS, VoiceOver reads Tab accessibility role elements as "tab description" rather than "tab". See issue facebook#30589 and facebook#30610

Looking at the file history the bug appears to have been introduced in facebook#27995

## Changelog

[iOS] [Fixed] - Tab Accessibility Role had incorrect localization string

Pull Request resolved: facebook#30689

Test Plan: Tested with voice over using the RNTester app

Reviewed By: PeteTheHeat

Differential Revision: D25926488

Pulled By: mdvacca

fbshipit-source-id: 525878e5c2a6b10e841708db78469617db487a8b

Author: adkenyon

React/AccessibilityResources/en.lproj/Localizable.strings

@@ -14,7 +14,7 @@
 "scrollbar"="scroll bar";
 "spinbutton"="spin button";
 "switch"="switch";
-"tab"="tab description";
+"tab"="tab";
 "tablist"="tab list";
 "timer"="timer";
 "toolbar"="tool bar";