Use the term "tags" in documentation consistently

See gh-39125

spring-boot-project/spring-boot-docs/src/docs/asciidoc/actuator/observability.adoc

@@ -9,7 +9,7 @@ To create your own observations (which will lead to metrics and traces), you can
 
 include::code:MyCustomObservation[]
 
-NOTE: Low cardinality key-values will be added to metrics and traces, while high cardinality key-values will only be added to traces.
+NOTE: Low cardinality tags will be added to metrics and traces, while high cardinality tags will only be added to traces.
 
 Beans of type `ObservationPredicate`, `GlobalObservationConvention`, `ObservationFilter` and `ObservationHandler` will be automatically registered on the `ObservationRegistry`.
 You can additionally register any number of `ObservationRegistryCustomizer` beans to further configure the registry.
@@ -27,10 +27,10 @@ Read more about it https://jdbc-observations.github.io/datasource-micrometer/doc
 TIP: Observability for R2DBC is built into Spring Boot.
 To enable it, add the `io.r2dbc:r2dbc-proxy` dependency to your project.
 
-[[actuator.observability.common-key-values]]
-=== Common Key-Values
-Common key-values are generally used for dimensional drill-down on the operating environment, such as host, instance, region, stack, and others.
-Common key-values are applied to all observations as low cardinality key-values and can be configured, as the following example shows:
+[[actuator.observability.common-tags]]
+=== Common tags
+Common tags are generally used for dimensional drill-down on the operating environment, such as host, instance, region, stack, and others.
+Common tags are applied to all observations as low cardinality tags and can be configured, as the following example shows:
 
 [source,yaml,indent=0,subs="verbatim",configprops,configblocks]
 ----
@@ -41,7 +41,7 @@ Common key-values are applied to all observations as low cardinality key-values
 	      stack: "prod"
 ----
 
-The preceding example adds `region` and `stack` key-values to all observations with a value of `us-east-1` and `prod`, respectively.
+The preceding example adds `region` and `stack` tags to all observations with a value of `us-east-1` and `prod`, respectively.
 
 [[actuator.observability.preventing-observations]]
 === Preventing Observations