Add 'Alt + click' feature to exclude labels (#8199)

Add 'Alt + click' and 'Alt +enter' feature to exclude particular labels on searching for issues.

options/locale/locale_en-US.ini

@@ -802,6 +802,7 @@ issues.delete_branch_at = `deleted branch <b>%s</b> %s`
 issues.open_tab = %d Open
 issues.close_tab = %d Closed
 issues.filter_label = Label
+issues.filter_label_exclude = `Use <code>alt</code> + <code>click/enter</code> to exclude labels`
 issues.filter_label_no_select = All labels
 issues.filter_milestone = Milestone
 issues.filter_milestone_no_select = All milestones