Proposition - add pending change icon

[godzil3]

Hi,

i'm aware in github contributing - it's proposal, adding pending change icon to link like

.nav-item.menu-pending a::before {
--content: "\f254";

webtrees-theme-modern/resources/css/customizations/enable-menu-icons.css

Line 70 in 7b47ce8

--content: "\f007";