Doc: Split up the "Adding Libraries to Projects" topic

- Turn the topic into a how-to topic
- Turn the example into a tutorial
- Mark the information as qmake-specific
- Add links to CMake information

Task-number: QTCREATORBUG-29361
Change-Id: I42befbf15ad8a0eba7e26a0a69e6d1963d2ce5be
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

doc/qtcreator/src/howto/creator-only/creator-how-tos.qdoc

@@ -61,6 +61,7 @@
 
     \list
         \li \l {Add a license header template for C++ code}
+        \li \l {Add libraries to projects}
         \li \l {Add subprojects to projects}
         \li \l {Create C++ classes}
         \li \l {Create files}