clarify description of the partition by field for SLOs

docs/en/observability/slo-create.asciidoc

@@ -46,7 +46,7 @@ When defining a custom KQL SLI, set the following fields:
 * *Query filter* — A KQL filter to specify relevant criteria by which to filter the index documents.
 * *Good query* — The query yielding events that are considered good or successful. For example, `nested.field.response.latency <= 100 and nested.field.env : “production”`
 * *Total query* — The query yielding all events to take into account for computing the SLI. For example, `nested.field.env : “production”`.
-* *Partition by* — Create an SLO for each value of the field you enter. 
+* *Partition by* — The field used to partition the data based on the values of the specific field. For example, you could partition by the `url.domain` field, which would create individual SLOs for each value of the selected field.
 
 [discrete]
 [[custom-metric-sli]]
@@ -70,7 +70,7 @@ When defining a custom metric SLI, set the following fields:
 ** *Metric [A-Z]* — The field that is aggregated using the `sum` aggregation for total events. For example, `processor.processed`
 ** *Filter [A-Z]* — The filter to apply to the metric for total events. For example, `"processor.outcome: *"`
 ** *Equation* — The equation that calculates the total metric. For example, `A`.
-* *Partition by* — Create an SLO for each value of the field you enter. 
+* *Partition by* — The field used to partition the data based on the values of the specific field. For example, you could partition by the `url.domain` field, which would create individual SLOs for each value of the selected field.
 
 [discrete]
 [[histogram-metric-sli]]
@@ -100,7 +100,7 @@ When defining a histogram metric SLI, set the following fields:
 ** *From* — (`range` aggregation only) The starting value of the range for total events. For example, `0`.
 ** *To* — (`range` aggregation only) The ending value of the range for total events. For example, `100`.
 ** *KQL filter* — The filter for total events. For example, `"processor.outcome : *"`.
-* *Partition by* — Create an SLO for each value of the field you enter. 
+* *Partition by* — The field used to partition the data based on the values of the specific field. For example, you could partition by the `url.domain` field, which would create individual SLOs for each value of the selected field.
 
 [discrete]
 [[apm-latency-and-availability-sli]]