[a11y] Improve accessibility label for Join WiFi button in tray.

This CL changes the accessibility label for Join Other button in tray
menu from "Join other..." to "Join other WiFi networks" to give more
context when using screen readers.

Fixed: 1027362
Change-Id: Id88e17add4fadd51671ebcfcbd40835a2564a114
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1949529Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Azeem Arshad <azeemarshad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721557}

ash/ash_strings.grd

@@ -992,7 +992,7 @@ This file contains the strings for ash.
         Network settings
       </message>
       <message name="IDS_ASH_STATUS_TRAY_OTHER_WIFI" desc="The label used for the item to display other Wi-Fi networks.">
-        Join other...
+        Join other Wi-Fi networks
       </message>
       <message name="IDS_ASH_STATUS_TRAY_EXTENSION_CONTROLLED_WIFI" desc="The accessible text for the badge in the detailed network list indicating that the respective network's configuration may be controlled by an extension.">
         The extension "<ph name="EXTENSION_NAME">$1<ex>Nexus S</ex></ph>" can help connect to this network.