[docs] UI implications of transaction name and type (elastic#2167)

docs/guide/apm-data-model.asciidoc

@@ -97,6 +97,17 @@ which are points in time relative to the start of the transaction with some labe
 In addition, agents provide options for users to capture custom <<metadata, metadata>>.
 Metadata can be indexed - <<labels-fields,`labels`>>, or not-indexed - <<custom-fields,`custom`>>.
 
+Transactions are grouped by their `type` and `name` in the APM UI's
+{kibana-ref}/transactions.html[Transaction overview].
+If you're using a supported framework, APM agents will automatically handle the naming for you.
+If you're not, or if you wish to override the default,
+all agents have API methods to manually set the `type` and `name`.
+
+* `type` should be a keyword of specific relevance in the service's domain,
+e.g. `request`, `backgroundjob`, etc.
+* `name` should be a generic designation of a transaction in the scope of a single service,
+e.g. `GET /users/:id`, `UsersController#show`, etc.
+
 TIP: Most agents limit keyword fields (e.g. `labels`) to 1024 characters,
 non-keyword fields (e.g. `span.db.statement`) to 10,000 characters.