go install needs version to be specified

Signed-off-by: Hercules Merscher <[email protected]>

Author: bitmaybewise

examples/rack/run

@@ -20,8 +20,8 @@ if ! installed vegeta; then
 		fatal "Could not find go. Either run the examples manually or install"
 	fi
 
-	go get github.com/tsenart/vegeta
-	go install github.com/tsenart/vegeta
+	go get github.com/tsenart/vegeta # older versions of Go
+	go install github.com/tsenart/vegeta@latest # newer versions of Go
 fi
 
 PORT=5000