doxygen: fix duplicated intro sections

elm_intro.h.in

@@ -4,7 +4,7 @@
  * @version @VMAJ@.@VMIN@.@VMIC@
  * @date 2008-2014
  *
- * @section intro What is Elementary?
+ * @section elm_intro What is Elementary?
  *
  * This is a VERY SIMPLE toolkit. It is not meant for writing extensive desktop
  * applications (yet). Small simple ones with simple needs.

src/lib/ecore_imf/Ecore_IMF.h

@@ -47,7 +47,7 @@ extern "C" {
  * @defgroup Ecore_IMF_Context_Group Ecore Input Method Context Functions
  * @ingroup Ecore_IMF_Lib_Group
  *
- * @section intro Introduction
+ * @section ecore_imf_intro Introduction
  *
  * Functions that operate on Ecore Input Method Context objects.
 

src/lib/edje/edje_lua2.c

@@ -18,7 +18,7 @@
 /**
    @page luaref Edje Lua scripting
 
-   @section intro Introduction
+   @section edje_lua_intro Introduction
 
    Lua is intended for script-only objects at this point (with embryo left
    for augmenting standard programs). Since script-only objects effectively

src/lib/elua/Elua.h

@@ -7,7 +7,7 @@
 
 /**
  *
- * @section intro Elua library
+ * @section elua_intro Elua library
  *
  * The Elua library was created to ease integration of EFL Lua into other EFL
  * libraries or applications. Using the Elua library you can easily create a
@@ -53,7 +53,7 @@ extern "C" {
  *
  * @date 2015 (created)
  *
- * @section toc Table of Contents
+ * @section elua_toc Table of Contents
  *
  * @li @ref elua_main_intro
  * @li @ref elua_main_compiling