Docs redesign (#728)

* Adding a dark mode
* Adding reference for types to summary pages
* Adding API Reference
* Adding modifiers to methods/fields/etc
* Minimizing files input
* Caching a lot of the output pages
* Cache only for each execution
* Adding API references to existing docs

docs/input/api/Sections/_Value.cshtml

@@ -0,0 +1,12 @@
+@using Statiq.CodeAnalysis
+@using Docs.Extensions
+@{
+    IDocument type = Document.GetDocument(CodeAnalysisKeys.Type);
+    string value = Document.GetString(CodeAnalysisKeys.Value);
+}
+
+@if (type is object && !string.IsNullOrWhiteSpace(value))
+{
+    <p>@Context.GetTypeLink(type)</p>
+    <p>@Html.Raw(value)</p>
+}