adding some comments and fixing docs debug template example

DOCS.md

@@ -130,7 +130,7 @@ notify:
       - http://tower.example.com/api/v1/job_templates/44/launch/
       - http://tower.example.com/api/v1/job_templates/45/launch/
       content_type: application/json
-      template: '{"name": "project.deploy","extra_vars": "{\"env\": \"dev\",\"git_branch\": \"{{ .Build.Branch }}\",\"hipchat_token\": \"$$HIPCHAT_TOKEN\"}"}'
+      template: '{"name": "project.deploy","extra_vars": "{\"env\": \"dev\",\"git_branch\": \"{{ build.branch }}\",\"hipchat_token\": \"$$HIPCHAT_TOKEN\"}"}'
 ```
 
 Example of a debug print result:

webhook.go

@@ -1,5 +1,6 @@
 package main
 
+// Webhook represents a webhook.
 type Webhook struct {
 	Urls        []string          `json:"urls"`
 	Debug       bool              `json:"debug"`
@@ -10,6 +11,7 @@ type Webhook struct {
 	ContentType string            `json:"content_type"`
 }
 
+// BasicAuth represents a HTTP basic authentication username and password.
 type BasicAuth struct {
 	Username string `json:"username"`
 	Password string `json:"password"`