[ci skip] Fix class reference sections of Image_lib, Parser and User agent docs
diff --git a/user_guide_src/source/libraries/user_agent.rst b/user_guide_src/source/libraries/user_agent.rst
index af76cfa..1b6a298 100644
--- a/user_guide_src/source/libraries/user_agent.rst
+++ b/user_guide_src/source/libraries/user_agent.rst
@@ -72,7 +72,7 @@
 Class Reference
 ***************
 
-.. class: CI_User_agent
+.. class:: CI_User_agent
 
 	.. method:: is_browser([$key = NULL])