Documentation: Fix Android Authenticator pref name

tools/android/kerberos/README.md

 ## Kerberos Test Utils
 
 Simple app and scripts used to test Kerberos auth on Chrome and WebView.
 
 
 ### Setup
 
 #### 1: Build and install the authenticator app
 
 See the next section for more info about the app.
@@ skipping 17 matching lines @@
     $CHROMIUM_SRC/build/android/adb_chrome_public_command_line \
     '--auth-server-whitelist="*" \
     --auth-spnego-account-type="org.chromium.tools.SpnegoAuthenticator"'
     ```
 
  -  By setting policies
 
     The policies to set are:
 
      *   AuthServerWhitelist: `*`
-     *   AuthSpnegoAccountType: `org.chromium.tools.SpnegoAuthenticator`
+     *   AuthAndroidNegotiateAccountType: `org.chromium.tools.SpnegoAuthenticator`
 
     To set them you have to be able to set restrictions for apps on the device.
     This can be achieved using the TestDPC app ([Play store][testdpc-play],
     [Github][testdpc-gh]), which is made for testing enterprise related Android
     features, including app restrictions.
 
     Set it up, then search for Chrome under "Manage app restrictions", tap
     "Load manifest restrictions" and change the value for the restrictions
     mentioned above.
 
@@ skipping 25 matching lines @@
  -  Set up up to 2 accounts.
  -  Account 1 will start authenticated.
  -  Account 2 will start unauthenticated. The first token request will require
     an additional confirmation step.
  -  Accounts can be added and removed from the Android account settings screen
 
 [testdpc-play]: https://play.google.com/store/apps/details?id=com.sample.android.testdpc
 [testdpc-gh]: https://github.com/googlesamples/android-testdpc
 [crwiki]:https://sites.google.com/a/chromium.org/dev/developers/design-documents/http-authentication/writing-a-spnego-authenticator-for-chrome-on-android
 [screenshot]:SpnegoAuthenticator/preview.png