Improve warmup behavior configuration in Couchbase Server

Replaced `warmup_min_memory_threshold` and `warmup_min_items_threshold` parameters with a unified `warmup_behavior` setting. The new parameter offers three modes: `blocking`, `background`, and `none`, providing more flexibility and faster bucket availability.

Author: RayOffiah

modules/introduction/partials/new-features-80.adoc

@@ -37,14 +37,19 @@ The previous warmup behavior was to load values and not complete warmup until th
 * The bucket low watermark (i.e., 75% of the Bucket quota)
 --
 +
-This could take considerable time, and during the warmup process, 
-the bucket is unavailable to the nodes. + 
+*Resolution:* Couchbase Server removes the `warmup_min_memory_threshold` and `warmup_min_items_threshold` parameters,
+and adds a new parameter: `warmup_behavior`. 
+This new parameter  can be used to change the thresholds using a single command. 
 +
-*Resolution:* Couchbase Server will now continue to page in items, even after the `warmup_min_items_threshold` has been reached.
-Therefore, if the `warmup_min_items_threshold` is set to 10%,
-then only 10% of the data items would need to be paged in before the warmup is flagged as complete.
-For larger data sets, the bucket will be available in a faster time frame,
-while the server will still make use of available memory.
+`warmup_behavior` takes one of three settings:
++
+[horizontal]
+`blocking`:::
+Warmup behaves the same as it did before with no secondary warmup.
+`background`:::
+Warmup now loads items in the background, allowing the bucket to have write availability much quicker than blocking.
+`none`:::
+Warmup is disabled; the bucket comes online with no items loaded.
 
 https://jira.issues.couchbase.com/browse/MB-64071[MB-64071]::
 Couchbase Server has a new metric