Use updated donation link; add button to nav

[nonprofittechy]

[samglover]

Some styling suggestions, but looks good to me. Thanks!

[samglover]

This rounds the button corners to match the search field and adds the same spacing around the button as the GitHub and dark mode icons have. I also removed !important since the custom class gives enough specificity.

.navbar-donate-button {
  background-color: var(--suffolk-light-gold);
  color: var(--suffolk-dark-blue);
  border-radius: 9999px;
  font-weight: 600;
  margin-right: calc(.25 * var(--ifm-navbar-item-padding-horizontal));
  margin-left: calc(.25 * var(--ifm-navbar-item-padding-horizontal));
  padding: 0.375rem 0.75rem;

  &:hover {
    background-color: var(--suffolk-dark-gold);
    color: White;
    text-decoration: none;
  }
}