Corrects the default max spaces in non-serverless docs (#203857)

## Summary

The max spaces is described as 100, but should be 1000 by default only
in our non-serverless offerings. Only serverless is currently limited to
100.

See
https://www.elastic.co/guide/en/kibana/current/xpack-spaces.html#spaces-managing

---------

Co-authored-by: wajihaparvez <wajiha.parvez@elastic.co>

docs/spaces/index.asciidoc

@@ -23,7 +23,7 @@ The `kibana_admin` role or equivalent is required to manage **Spaces**.
 === Create a space
 
 [[spaces-control-feature-visibility]]
-You can have up to 100 spaces. 
+You can have up to 1,000 spaces by default. The maximum number of spaces can be configured by the `xpack.spaces.maxSpaces` setting (refer to <<spaces-settings-kb, Spaces settings in {kib}>>).
 
 . Select *Create space* and provide a name, description, and URL identifier.
 +