[8.x] Spaces in serverless (backport #5813) (#6048)

* Spaces in serverless (#5813)

* Add previously omitted spaces page, align with ESS

* Fix typo in description frontmatter

* Minor edit

* Update "Data views in Elastic Security"

Align across platforms, and omit "feature visibility" since it's unavailable in security

* Update "Timeline"

* Update "Timeline templates"

* Update link to general docs on spaces

This link will be broken until elastic/docs-content#55 is merged

* Fix links: targets from stateful to serverless

(cherry picked from commit 686800d)

# Conflicts:
#	docs/serverless/explore/data-views-in-sec.mdx
#	docs/serverless/investigate/timeline-templates-ui.mdx
#	docs/serverless/investigate/timelines-ui.mdx
#	docs/serverless/sec-requirements.mdx
#	docs/serverless/serverless-security.docnav.json

* Delete docs/serverless directory and its contents

---------

Co-authored-by: Joe Peeples <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

docs/events/timeline-templates.asciidoc

@@ -136,7 +136,7 @@ NOTE: You cannot delete prebuilt templates.
 == Export and import Timeline templates
 
 You can import and export Timeline templates, which enables importing templates
-from one {kib} space or instance to another. Exported templates are saved in an `ndjson` file.
+from one space or {elastic-sec} instance to another. Exported templates are saved in an `ndjson` file.
 
 . Go to *Timelines* -> *Templates*.
 . To export templates, do one of the following:

docs/events/timeline-ui-overview.asciidoc

@@ -171,7 +171,7 @@ then select an action from the *Bulk actions* menu.
 == Export and import Timelines
 
 You can export and import Timelines, which enables you to share Timelines from one
-{kib} space or instance to another. Exported Timelines are saved as `.ndjson` files.
+space or {elastic-sec} instance to another. Exported Timelines are saved as `.ndjson` files.
 
 To export Timelines:
 

docs/getting-started/data-views-in-sec.asciidoc

@@ -33,7 +33,7 @@ NOTE: You cannot update the data view for the Alerts page. This includes referen
 [[default-data-view-security]]
 == The default {data-source}
 
-The default {data-source} is defined by the `securitySolution:defaultIndex` setting, which you can modify in {kib}'s advanced settings (**Stack Management** > **Advanced Settings** > **Security Solution**). To learn more about this setting, including its default value, refer to {security-guide}/advanced-settings.html#update-sec-indices[Advanced settings].
+The default {data-source} is defined by the `securitySolution:defaultIndex` setting, which you can modify in {security-guide}/advanced-settings.html#update-sec-indices[advanced settings].
 
 The first time a user visits {elastic-sec} within a given {kib} {kibana-ref}/xpack-spaces.html[space], the default {data-source} generates in that space and becomes active. 
 

docs/getting-started/security-spaces.asciidoc

@@ -2,13 +2,13 @@
 = Spaces and {elastic-sec}
 
 {elastic-sec} supports the organization of your security operations into
-logical instances with the {kibana-ref}/xpack-spaces.html[{kib} spaces]
+logical instances with the {kibana-ref}/xpack-spaces.html[spaces]
 feature. Each space in {kib} represents a separate logical instance of
 {elastic-sec} in which detection rules, rule exceptions, value lists,
 alerts, Timelines, cases, and {kib} advanced settings are private to the
 space and accessible only by users that have role privileges to
-access the space. For details about configuring privileges for
-{es} and {kib}, refer to <<detections-permissions-section>>.
+access the space. For details about privileges for
+{elastic-sec} and specific features, refer to <<sec-requirements>>.
 
 For example, if you create a `SOC_prod` space in which you load and
 activate all the {elastic-sec} prebuilt detection rules, these rules and
@@ -22,7 +22,7 @@ the `SOC_dev` space, and they will run independently of those in the
 [NOTE]
 ===== 
 By default, alerts created by detection rules are stored in {es} indices
-under the `.alerts-security.alerts-<Kibana-space>` index pattern, and they may be
+under the `.alerts-security.alerts-<space-name>` index pattern, and they may be
 accessed by any user with role privileges to access those
 {es} indices. In our example above, any user with {es} privileges to access
 `.alerts-security.alerts-SOC_prod` will be able to view `SOC_prod` alerts from