Doc: Add a doc project for the Fossil plugin

Change-Id: Ic465b8838f090688fab2fc966fa3fbf7409c13a2
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

plugins/fossil/fossilplugin.cpp

@@ -43,6 +43,7 @@
 #include <coreplugin/id.h>
 #include <coreplugin/vcsmanager.h>
 #include <coreplugin/coreconstants.h>
+#include <coreplugin/helpmanager.h>
 #include <coreplugin/icore.h>
 #include <coreplugin/idocument.h>
 #include <coreplugin/documentmanager.h>
@@ -152,6 +153,9 @@ bool FossilPlugin::initialize(const QStringList &arguments, QString *errorMessag
 
     createSubmitEditorActions();
 
+    Core::HelpManager::registerDocumentation({Core::ICore::documentationPath()
+                                              + "/fossil.qch"});
+
     return true;
 }