patch source for a couple code block changes

builder/azure/arm/config.go

@@ -340,7 +340,7 @@ type Config struct {
 	// tags to the image to ensure this information is not lost. The following
 	// tags are added.
 	//
-	// ```
+	// ```text
 	// 1.  PlanName
 	// 2.  PlanProduct
 	// 3.  PlanPublisher

builder/virtualbox/common/export_config.go

@@ -39,7 +39,7 @@ type ExportConfig struct {
 	// packer call like this (shell `>` continuation character snipped for easier
 	// copy & paste):
 	//
-	// ``` shell
+	// ```shell
 	// vm_description='some
 	// multiline
 	// description'