[observability_pipelines] Clarify Grok source description (DataDog#3941)

Co-authored-by: ci.datadog-api-spec <packages@datadoghq.com>

Author: api-clients-generation-pipeline[bot]

.generator/schemas/v2/openapi.yaml

@@ -46179,7 +46179,7 @@ components:
             $ref: "#/components/schemas/ObservabilityPipelineParseGrokProcessorRuleMatchRule"
           type: array
         source:
-          description: The name of the field in the log event to apply the Grok rules to.
+          description: The value of the source field in log events to be processed by the Grok rules.
           example: "message"
           type: string
         support_rules:

api/datadogV2/model_observability_pipeline_parse_grok_processor_rule.go

@@ -16,7 +16,7 @@ type ObservabilityPipelineParseGrokProcessorRule struct {
 	// A list of Grok parsing rules that define how to extract fields from the source field.
 	// Each rule must contain a name and a valid Grok pattern.
 	MatchRules []ObservabilityPipelineParseGrokProcessorRuleMatchRule `json:"match_rules"`
-	// The name of the field in the log event to apply the Grok rules to.
+	// The value of the source field in log events to be processed by the Grok rules.
 	Source string `json:"source"`
 	// A list of Grok helper rules that can be referenced by the parsing rules.
 	SupportRules []ObservabilityPipelineParseGrokProcessorRuleSupportRule `json:"support_rules,omitempty"`