Document our functions, as an faq?

We often have folks with issues with `{% link %}`, especially including the `#fragment` portion of the URL inside the filename which isn't correct due to how link works.

Ours

```
1452 {% snippet
2519 {% tool
1 {% workflow
22 {% color
8881 {% icon
```

Plugins

```
6 {% bibliography
1362 {% cite
```

Jekyll

```
472 {% assign
27 {% capture
6 {% comment
1 {% dump
529 {% if
180 {% else
31 {% elsif
1 {% file
164 {% for
332 {% include
1056 {% link
292 {% raw
13 {% set
53 {% unless
```