qdoc: Fix string used in compatibility members page

Add a missing space in the comment generated at the top of the
compatibility members page.

Change-Id: I21e010f9fca41346bb50c4b400325b18ff672738
Reviewed-by: Martin Smith <martin.smith@digia.com>

src/tools/qdoc/htmlgenerator.cpp

@@ -2658,7 +2658,7 @@ QString HtmlGenerator::generateLowStatusMemberFile(InnerNode *inner,
         out() << "<p><b>The following members of class "
               << "<a href=\"" << linkForNode(inner, 0) << "\">"
               << protectEnc(inner->name()) << "</a>"
-              << "are part of the "
+              << " are part of the "
                  "Qt compatibility layer.</b> We advise against "
                  "using them in new code.</p>\n";
     }