Updated docs with a fast intro

samples/samples-standalone/http-client/src/main/java/com/example/loan/LoanApplicationService.java

@@ -43,10 +43,12 @@ public class LoanApplicationService {
 		HttpHeaders httpHeaders = new HttpHeaders();
 		httpHeaders.add(HttpHeaders.CONTENT_TYPE, FRAUD_SERVICE_JSON_VERSION_1);
 
+		// tag::client_call_server[]
 		ResponseEntity<FraudServiceResponse> response =
 				restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
 						new HttpEntity<>(request, httpHeaders),
 						FraudServiceResponse.class);
+		// end::client_call_server[]
 
 		return response.getBody();
 	}

samples/samples-standalone/http-client/src/test/groovy/com/example/loan/LoanApplicationServiceSpec.groovy

@@ -30,6 +30,7 @@ class LoanApplicationServiceSpec extends Specification {
 			loanApplication.rejectionReason == null
 	}
 
+	// tag::client_tdd[]
 	def 'should be rejected due to abnormal loan amount'() {
 		given:
 			LoanApplication application =
@@ -40,5 +41,6 @@ class LoanApplicationServiceSpec extends Specification {
 			loanApplication.loanApplicationStatus == LoanApplicationStatus.LOAN_APPLICATION_REJECTED
 			loanApplication.rejectionReason == 'Amount too high'
 	}
+	// end::client_tdd[]
 
 }