fix: add api_version breadcrumb to client docs

gapic-generator/lib/gapic/schema/wrappers.rb

@@ -347,6 +347,18 @@ def full_name
         @address.join "."
       end
 
+      # @private
+      # This is an override that adds mention of the client's service and API
+      # version if the service has a google.api.api_version set.
+      def docs_leading_comments disable_xrefs: false, transport: nil
+        str = super(disable_xrefs: disable_xrefs, transport: transport)
+        if !str || api_version.nil? || api_version.empty?
+          return str
+        end
+
+        "#{str.strip}\n\nThis client uses #{name} version #{api_version}."
+      end
+
       # @!method name
       #   @return [String] the unqualified name of the service.
       # @!method options

shared/output/gapic/templates/showcase/lib/google/showcase/v1beta1/echo.rb

@@ -47,6 +47,8 @@ module V1beta1
       # 'x-goog-request-params' metadata key on any method to have the values
       # echoed in the response headers.
       #
+      # This client uses Echo version v1_20240408.
+      #
       # @example Load this service and instantiate a gRPC client
       #
       #     require "google/showcase/v1beta1/echo"

shared/output/gapic/templates/showcase/lib/google/showcase/v1beta1/echo/client.rb

@@ -44,6 +44,8 @@ module Echo
         # 'x-goog-request-params' metadata key on any method to have the values
         # echoed in the response headers.
         #
+        # This client uses Echo version v1_20240408.
+        #
         class Client
           # @private
           API_VERSION = "v1_20240408"

shared/output/gapic/templates/showcase/lib/google/showcase/v1beta1/echo/rest.rb

@@ -47,6 +47,8 @@ module V1beta1
       # 'x-goog-request-params' metadata key on any method to have the values
       # echoed in the response headers.
       #
+      # This client uses Echo version v1_20240408.
+      #
       # To load this service and instantiate a REST client:
       #
       #     require "google/showcase/v1beta1/echo/rest"

shared/output/gapic/templates/showcase/lib/google/showcase/v1beta1/echo/rest/client.rb

@@ -46,6 +46,8 @@ module Rest
           # 'x-goog-request-params' metadata key on any method to have the values
           # echoed in the response headers.
           #
+          # This client uses Echo version v1_20240408.
+          #
           class Client
             # @private
             API_VERSION = "v1_20240408"