Add initial version of schema specification site

After running the util/generate_docs.py script to parse and extract
the metadata term specifications and their controlled vocabularies,
we use Hugo to generate the HTML site. The HTML site uses Bootstrap
with several ISEAL brand colors gleaned from the corporate website.

site/source/scss/main.scss

@@ -0,0 +1,53 @@
+/*
+   From Bootstrap v5.0 sticky footer example
+   See:  https://getbootstrap.com/docs/5.0/examples/sticky-footer/
+*/
+
+// this is the second dark blue, slightly lighter than the primary
+$iseal-dark-blue: #0e304a;
+// another light blue
+$iseal-light-blue: #328cd1;
+
+/*
+   Some styles inspired from the Dublin Core DCTERMS website, see:
+   https://www.dublincore.org/specifications/dublin-core/dcmi-terms/
+*/
+
+body {
+    /* for the "scroll spy" navbar feature */
+    position: relative;
+    color: $primary;
+    background-color: $white;
+    font-family: Calibri,Candara,Segoe,Segoe UI,Optima,Arial,sans-serif;
+}
+
+div.badge-required {
+    float: right;
+}
+
+td.field-name {
+    text-align: right;
+    font-weight: 700;
+}
+
+.table {
+    color: $primary;
+}
+
+/* Override Bootstrap's top border on tbody */
+.table>:not(:first-child) {
+    border-top: 2px solid $iseal-light-blue;
+}
+
+h1, h2, h3 {
+    color: $primary;
+}
+
+.footer {
+  color: $white;
+  background-color: $iseal-dark-blue;
+
+  a, a:hover {
+    color: inherit;
+  }
+}