Adjust IDS_LOGIN_DEVICE_MANAGED_BY_NOTICE for FlexOrgs

Change the domain placeholder name to manager and adjust its description
and add screenshot to make it easier for the translators to understand
the usage of the text.

Strings that are constructed with this message already use the manager
rather than the domain.

Bug: b:172678338
Test: None
Change-Id: Ife33997d6acd0e2d51d4c7a70f9f401816dcaa33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2635141Reviewed-by: Brian Malcolm <bmalcolm@chromium.org>
Commit-Queue: Jana Grill <janagrill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845200}

chrome/app/chromeos_strings.grdp

@@ -1293,8 +1293,8 @@
   <message name="IDS_LOGIN_ACCOUNT_SETUP_CANCEL_DIALOG_YES" desc="Text to show on button to accept cancelation.">
     Yes
   </message>
-  <message name="IDS_LOGIN_DEVICE_MANAGED_BY_NOTICE" desc="Text for notifications showing that this is managed device.">
-    Managed by <ph name="DOMAIN">$1<ex>acmecorp.com</ex></ph>
+  <message name="IDS_LOGIN_DEVICE_MANAGED_BY_NOTICE" desc="Text for notifications showing that this is managed device. MANAGER can be a domain or an email address.">
+    Managed by <ph name="MANAGER">$1<ex>acmecorp.com</ex></ph>
   </message>
   <message name="IDS_LOGIN_FATAL_ERROR_NO_ACCOUNT_DETAILS" desc="Message to show when the authentication could not be completed because the user's account details could not be retrieved.">
     Sign-in failed because your account details could not be retrieved. Please contact your administrator or try again.

chrome/app/chromeos_strings_grdp/IDS_LOGIN_DEVICE_MANAGED_BY_NOTICE.png.sha1

+d2b23d42a6caad61fc56bdff12da4b80082a8dfa
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