Add warning to policy docs about disabling extensions using devtools.

components/policy/resources/policy_templates.json

Index: components/policy/resources/policy_templates.json
diff --git a/components/policy/resources/policy_templates.json b/components/policy/resources/policy_templates.json
index 3a35f179a38ec477c4c503222b870bed555e0bb3..04143dcec27052e1c757f4073b818444c205df84 100644
--- a/components/policy/resources/policy_templates.json
+++ b/components/policy/resources/policy_templates.json
@@ -1818,7 +1818,11 @@
 
           Users will be unable to uninstall extensions that are specified by this policy. If you remove an extension from this list, then it will be automatically uninstalled by <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph>. Extensions specified in this list are also automatically whitelisted for installation; the ExtensionsInstallBlacklist does not affect them.
 
-          If this policy is left not set the user can uninstall any extension  in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph>.''',
+          Note that the source code of any extension may be altered (potentially
+          rendering the extension dysfunctional) by using Developer Tools.  If

[bartfab (slow), 2015/03/03 21:25:31]

Nit: We use a single space after full stop in policy_templates.json.

[Thiemo Nagel, 2015/03/04 23:18:00]

Done.

+          this is a concern, the DeveloperToolsDisabled policy should be set.
+
+          If this policy is left not set the user can uninstall any extension in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph>.''',
           'label': '''Extension IDs and update URLs to be silently installed''',
         },
         {