A controller for serving arbitrary markdown documents from a directory, and having preprocessed keywords for writing.

DocumentationController.cs

public class DocumentationController : Controller
{
    private const string DefaultDocPage = "Overview";
    public ActionResult Index(string id = null)
    {
        ViewBag.HomeLinkPage = string.IsNullOrEmpty(id) || id == DefaultDocPage ? string.Empty : DefaultDocPage;
        if (string.IsNullOrEmpty(ViewBag.HomeLinkPage))
        {
            id = DefaultDocPage;
        }
        var filePath = Server.MapPath(Url.Content("~/Content/Documentation/" + id.Trim("/".ToCharArray()) + ".md"));
        if(!System.IO.File.Exists(filePath))
        {
            Response.StatusCode = (int)HttpStatusCode.NotFound;
            return null;
        }
        var contents = new StringBuilder(System.IO.File.ReadAllText(filePath));

        contents.Replace("{{AppRoot}}/", Url.Content("~"));
        contents.Replace("{{Documentation}}", Url.Content("~/Documentation"));
        contents.Replace("{{DocumentationImages}}", Url.Content("~/Content/Documentation/images"));
        contents.Replace("{{SupportLink}}", ConfigurationManager.AppSettings["SupportLink"]);
        return View("Index", (object)contents.ToString());
    }
}