Add Elasticsearch and Logstash output settings to Elastic Agent docs (#…

…460) (#1003)

* Add output settings to Elastic Agent docs

* Changes applied after merge to preserve earlier changes

* First batch of changes from the review

* Add missing proxy settings

* Add kerberos settings

* Add SSL settings

* Add ssl settings to logstash output docs

* Fix ssl examples

* Add link to pipeline ES docs

docs/en/ingest-management/elastic-agent/configuration/authentication/kerberos-shared-settings.asciidoc

@@ -0,0 +1,121 @@
+// These settings are shared across some inputs and outputs.
+
+// You can include this whole block, or individual settings
+// tag::kerberos-all-settings[]
+
+
+[cols="2*<a"]
+|===
+| Setting | Description
+
+// =============================================================================
+
+// tag::kerberos.auth_type-setting[]
+|
+[id="{type}-kerberos.auth_type-setting"]
+`kerberos.auth_type`
+
+| (string) The type of authentication to use with Kerberos KDC:
+
+`password`::
+When specified, also set `kerberos.username` and `kerberos.password`.
+
+`keytab`::
+When specified, also set `kerberos.username` and `kerberos.keytab`. The keytab
+must contain the keys of the selected principal, or authentication fails.
+
+*Default:* `password`
+
+// end::kerberos.auth_type-setting[]
+
+// =============================================================================
+
+// tag::kerberos.config_path[]
+|
+[id="{type}-kerberos.config_path"]
+`kerberos.config_path`
+
+| (string) Path to the `krb5.conf`. {agent} uses this setting to find the
+Kerberos KDC to retrieve a ticket.
+
+// end::kerberos.config_path[]
+
+// =============================================================================
+
+// tag::kerberos.enabled-setting[]
+|
+[id="{type}-kerberos.enabled-setting"]
+`kerberos.enabled`
+
+| (boolean) Enables or disables the Kerberos configuration.
+
+NOTE: Kerberos settings are disabled if either `enabled` is set to `false` or the
+`kerberos` section is missing.
+
+// end::kerberos.enabled-setting[]
+
+// =============================================================================
+
+// tag::kerberos.enable_krb5_fast[]
+|
+[id="{type}-kerberos.enable_krb5_fast"]
+`kerberos.enable_krb5_fast`
+
+| (boolean) If `true`, enables Kerberos FAST authentication. This may conflict
+with some Active Directory installations.
+
+*Default:* `false`
+
+// end::kerberos.enable_krb5_fast[]
+
+// =============================================================================
+
+// tag::kerberos.keytab[]
+|
+[id="{type}-kerberos.keytab"]
+`kerberos.keytab`
+
+| (string) If `kerberos.auth_type` is `keytab`, provide the path to the keytab
+of the selected principal.
+
+// end::kerberos.keytab[]
+
+// =============================================================================
+
+// tag::kerberos.password[]
+|
+[id="{type}-kerberos.password"]
+`kerberos.password`
+
+| (string) If `kerberos.auth_type` is `password`, provide a password for the
+selected principal.
+
+// end::kerberos.password[]
+
+// =============================================================================
+
+// tag::kerberos.realm[]
+|
+[id="{type}-kerberos.realm"]
+`kerberos.realm`
+
+| (string) Name of the realm where the output resides.
+
+// end::kerberos.realm[]
+
+// =============================================================================
+
+// tag::kerberos.username[]
+|
+[id="{type}-kerberos.username"]
+`kerberos.username`
+
+| (string) Name of the principal used to connect to the output.
+
+// end::kerberos.username[]
+
+// =============================================================================
+
+|===
+
+// end::kerberos-all-settings[]