Merge pull request #1953 from carolinux/doc-fix

Minor: Install instructions for debug mode

Author: m-kuhn

doc/linux.t2t

@@ -121,8 +121,9 @@ ccmake ..
 ```
 
 When you run ccmake (note the .. is required!), a menu will appear where
-you can configure various aspects of the build. If you do not have root
-access or do not want to overwrite existing QGIS installs (by your
+you can configure various aspects of the build. If you want QGIS to have
+debugging capabilities then set CMAKE_BUILD_TYPE to Debug. If you do not have
+root access or do not want to overwrite existing QGIS installs (by your
 packagemanager for example), set the CMAKE_INSTALL_PREFIX to somewhere you
 have write access to (I usually use ${HOME}/apps). Now press
 'c' to configure, 'e' to dismiss any error messages that may appear.