update help section with issues API docs

app/views/help/api.html.haml

 %h3 API
 .back_link
-  = link_to help_path do 
+  = link_to help_path do
     ← to index
 %hr
 
 %ol
-  %li 
+  %li
     %a{:href => "#README"} README
-  %li 
+  %li
     %a{:href => "#projects"} Projects
-  %li 
+  %li
     %a{:href => "#users"} Users
+  %li
+    %a{:href => "#issues"} Issues
 
 .file_holder#README
   .file_title
@@ -39,3 +41,13 @@
   .file_content.wiki
     = preserve do
       = markdown File.read(Rails.root.join("doc", "api", "users.md"))
+
+%br
+
+.file_holder#issues
+  .file_title
+    %i.icon-file
+    Issues
+  .file_content.wiki
+    = preserve do
+      = markdown File.read(Rails.root.join("doc", "api", "issues.md"))