add support for custom partials

site/pages/docs/index.md

@@ -20,6 +20,10 @@ learn about standard webdog pages here
 
 learn how to use webdog templates
 
+## <a href="webdog-html">webdog html</a>
+
+learn about webdog html extensions
+
 ## <a href="styling">styling</a>
 
 learn about webdog styling

site/pages/docs/webdog-html.md

@@ -0,0 +1,34 @@
+---
+title: webdog html
+template: docs.tera
+---
+
+# webdog html
+
+webdog adds some extensions to html to make building your site easier.
+
+## `wd-partial`
+
+any template can be used as a partial in another template or page.
+
+in a template like this:
+
+```html
+<p>this is a partial.</p>
+<p>the hi argument is {{ userdata.hi }}</p>
+<p>the hello argument is {{ userdata.hello }}</p>
+<div>
+  <p>and here's the inner content:
+  {{ page | safe }}
+</div>
+```
+
+simply include the `wd-partial` html tag like so:
+
+```html
+<wd-partial t="template-to-use.tera" hello="hi" hi="hello">
+  hiiiiiiiiiii~
+</wd-partial>
+```
+
+a `wd-partial` tag consists of the `t` attribute to determine the template and any number of additional arguments, which are passed on to the partial template.