Save the link color.

app/forms/hyrax/forms/admin/appearance.rb

@@ -75,6 +75,7 @@ def primary_button_focus_border_color
         def update!
           update_block('header_background_color', attributes[:header_background_color])
           update_block('header_text_color', attributes[:header_text_color])
+          update_block('link_color', attributes[:link_color])
           update_block('footer_link_color', attributes[:footer_link_color])
           update_block('primary_button_background_color', attributes[:primary_button_background_color])
         end

spec/forms/hyrax/forms/admin/appearance_spec.rb

@@ -0,0 +1,18 @@
+require 'spec_helper'
+
+RSpec.describe Hyrax::Forms::Admin::Appearance do
+  let(:form) { described_class.new({}) }
+
+  describe "update!" do
+    let(:block) { instance_double(ContentBlock) }
+
+    before do
+      allow(ContentBlock).to receive(:find_or_create_by).and_return(block)
+    end
+
+    it "calls update block 5 times" do
+      expect(block).to receive(:update!).exactly(5).times
+      form.update!
+    end
+  end
+end