Doc: Get Creator and Extending manuals to use new qdocconf variables.

-navigation variables for Qt 5.2's navigation bar
-buildversion is for including specific build information such
 as branch name and patch version

Change-Id: I4d36f1ea73b8c37ab787d154c9fdd91650305bc5
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

doc/config/qtcreator-developer.qdocconf

@@ -68,3 +68,6 @@ qhp.QtCreator.subprojects.manual.type = manual
 
 macro.see                       = "\\sa"
 macro.function                  = "\\fn"
+
+navigation.landingpage = "Extending Qt Creator Manual"
+buildversion = "Extending Qt Creator Manual $QTC_VERSION"

doc/config/qtcreator-project.qdocconf

@@ -34,3 +34,6 @@ qhp.QtCreator.subprojects.manual.type = manual
 
 macro.see                       = "\\sa"
 macro.function                  = "\\fn"
+
+navigation.landingpage = "Qt Creator Manual"
+buildversion = "Qt Creator Manual $QTC_VERSION"