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/config.toml

@@ -0,0 +1,16 @@
+title="ISEAL Schema"
+baseURL="https://alanorth.github.io/iseal-schema"
+languageCode = "en-us"
+enableRobotsTXT = true
+publishDir = "docs"
+disablePathToLower = true
+
+[permalinks]
+  terms = "/:slug/"
+
+[params]
+  # Site author
+  author = "Alan Orth"
+
+  # Description/subtitle for homepage
+  description = "Documenting metadata fields and controlled vocabularies for the ISEAL core schema."