Add role based auth to CloudWatch exporter doc (#3156)

* Add role based auth to CloudWatch exporter doc

Role based authentication is added for CloudWatch exporter that allows
to authenticate with users' AWS accounts and we need to document
configuration that needs to be done on the user side to make it work.

* add provider URLs and role example

* Clarify what the URL serves for

* chore: first go updating the configuration procedure.

* chore: updates after first review.

* chore: updates after first review.

* Update use-timescale/metrics-logging/integrations.md

Nice.

Co-authored-by: Danil Zhigalin <danil@timescale.com>
Signed-off-by: Iain Cox <iain@timescale.com>

* fix: update metatags for MDX.

* Replace trust policy to a role

AWS docs refer to this as a role. Make sure we are talking about the
same thing in our docs.

* Update use-timescale/metrics-logging/integrations.md

Co-authored-by: Nicolas Nosenzo <niconosenzo@gmail.com>
Signed-off-by: Iain Cox <iain@timescale.com>

---------

Signed-off-by: Iain Cox <iain@timescale.com>
Co-authored-by: niconosenzo <niconosenzo@gmail.com>
Co-authored-by: billy-the-fish <iain.cox@sarkdocumentation.com>
Co-authored-by: Iain Cox <iain@timescale.com>

_partials/_cloud-integrations-exporter-region.md

@@ -1,4 +1,4 @@
 <Highlight type="important">
-Your exporter must be in the same AWS region as your database service. If you
-have databases in multiple regions, you can create multiple exporters.
+Your exporter must be in the same AWS region as the Timescale Service it is attached to. 
+If you have Timescale Services running in multiple regions, create an exporter for each region. 
 </Highlight>