[DOCS] Moves Watcher troubleshooting page (#44144)

x-pack/docs/en/watcher/index.asciidoc

@@ -85,4 +85,6 @@ include::managing-watches.asciidoc[]
 
 include::example-watches.asciidoc[]
 
+include::troubleshooting.asciidoc[]
+
 include::limitations.asciidoc[]

x-pack/docs/en/watcher/troubleshooting.asciidoc

@@ -0,0 +1,69 @@
+[role="xpack"]
+[testenv="gold"]
+[[watcher-troubleshooting]]
+== Troubleshooting {watcher}
+[subs="attributes"]
+++++
+<titleabbrev>Troubleshooting</titleabbrev>
+++++
+
+[discrete]
+=== Dynamic mapping error when trying to add a watch
+
+If you get the _Dynamic Mapping is Disabled_ error when you try to add a watch,
+verify that the index mappings for the `.watches` index are available. You can
+do that by submitting the following request:
+
+[source,js]
+--------------------------------------------------
+GET .watches/_mapping
+--------------------------------------------------
+// CONSOLE
+
+//When testing is enabled, test [setup:my_active_watch]
+
+If the index mappings are missing, follow these steps to restore the correct
+mappings:
+
+. Stop the Elasticsearch node.
+. Add `xpack.watcher.index.rest.direct_access : true` to `elasticsearch.yml`.
+. Restart the Elasticsearch node.
+. Delete the `.watches` index:
++
+--
+[source,js]
+--------------------------------------------------
+DELETE .watches
+--------------------------------------------------
+// CONSOLE
+
+//When testing is enabled, test[skip:index deletion]
+--
+. Disable direct access to the `.watches` index:
+.. Stop the Elasticsearch node.
+.. Remove `xpack.watcher.index.rest.direct_access : true` from `elasticsearch.yml`.
+.. Restart the Elasticsearch node.
+
+[discrete]
+=== Unable to send email
+
+If you get an authentication error indicating that you need to continue the
+sign-in process from a web browser when Watcher attempts to send email, you need
+to configure Gmail to
+https://support.google.com/accounts/answer/6010255?hl=en[Allow Less Secure Apps to access your account].
+
+If you have two-step verification enabled for your email account, you must
+generate and use an App Specific password to send email from {watcher}. For more
+information, see:
+
+- Gmail: https://support.google.com/accounts/answer/185833?hl=en[Sign in using App Passwords]
+- Outlook.com: http://windows.microsoft.com/en-us/windows/app-passwords-two-step-verification[App passwords and two-step verification]
+
+[discrete]
+=== {watcher} not responsive
+
+Keep in mind that there's no built-in validation of scripts that you add to a
+watch. Buggy or deliberately malicious scripts can negatively impact {watcher}
+performance. For example, if you add multiple watches with buggy script
+conditions in a short period of time, {watcher} might be temporarily unable to
+process watches until the bad watches time out.