libgis: add missing space to G__usage_html()

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@70863 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/gis/parser_html.c

@@ -262,7 +262,7 @@ void G__usage_html(void)
 
                             if (thumbnails)
                                 fprintf(stdout, "<img height=\"12\" "
-                                        "style=\"max-width: 80;\""
+                                        "style=\"max-width: 80;\" "
                                         "src=\"%s/%s.png\" alt=\"%s\"> ",
                                         thumbnails, opt->opts[i], opt->opts[i]);
                         }