Doc: C and C++ compilers can now be added separately

Update screenshots.

Change-Id: I02be7d5be7865f58d6842be0e064a205034becf2
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

doc/src/projects/creator-projects-compilers.qdoc

@@ -82,8 +82,9 @@
     \list 1
 
         \li Select \uicontrol Tools > \uicontrol Options >
-            \uicontrol {Build & Run} > \uicontrol Compilers > \uicontrol Add
-            and select a compiler in the list.
+            \uicontrol {Build & Run} > \uicontrol Compilers > \uicontrol Add,
+            then select a compiler in the list, and then select \uicontrol C or
+            \uicontrol C++ to add a C or C++ compiler.
 
             \image qtcreator-toolchains.png
 
@@ -124,7 +125,8 @@
     \list 1
 
         \li Select \uicontrol Tools > \uicontrol Options > \uicontrol {Build & Run} >
-            \uicontrol Compilers > \uicontrol Add > \uicontrol Custom.
+            \uicontrol Compilers > \uicontrol Add > \uicontrol Custom >
+            \uicontrol C or \uicontrol C++.
 
         \li In the \uicontrol Name field, enter a name for the compiler.
 

doc/src/projects/creator-projects-targets.qdoc

@@ -91,8 +91,8 @@
             image is located. If you are not cross-compiling, leave this field
             empty.
 
-        \li In the \uicontrol {Compiler} field, select the compiler required
-            to build the project. You can add compilers to the list
+        \li In the \uicontrol {Compiler} field, select the C or C++ compiler
+            used to build the project. You can add compilers to the list
             if they are installed on the development PC, but were not detected
             automatically. For more information, see \l{Adding Compilers}.