Doc: Remove codeindent from documentation configuration

A default indent of 1 was defined for code snippets. It was overridden
by the template, and most likely left there as an oversight. Now, with
QDoc and the templates from Qt 5.6 it does have an effect, and makes
the style look worse and copy-pasting code more cumbersome.

Change-Id: I37a0facd4c03566eaf295a2cc391fa328f50c14d
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

doc/config/qt-defines.qdocconf

@@ -14,5 +14,3 @@ defines                 = Q_QDOC \
                           $QTC_LICENSE_TYPE
 
 versionsym              = QT_VERSION_STR
-
-codeindent              = 1