Update docs

behaviors/magic-button.md

@@ -7,6 +7,7 @@ Append a magic button to an input.
 * **field** _(optional)_ a field to grab the value from
 * **component** _(optional)_ a name of a component to grab the component ref from
 * **transform** _(optional)_ a transform to apply to the grabbed value
+* **transformArg** _(optional)_ an argument to pass through to the transform
 * **url** _(optional)_ to get data from
 * **property** _(optional)_ to get from the returned data
 * **moreMagic** _(optional)_ to run the returned value through more transforms, api calls, etc
@@ -17,6 +18,7 @@ Magic buttons are extremely powerful, but can be a little confusing to configure
 
 1. specify a `field` or `component`. The button will grab the value or ref, respectively
 2. specify a `transform`. Transforms are useful when doing api calls with that data
+2. specify a `transformArg` if you need to send more information to the transform.
 3. specify a `url` to do the api call against. It will do a GET request to `url + transformed data`
 4. specify a `property` to grab from the result of that api call. You can use `_.get()` syntax, e.g. `foo.bar[0].baz`
 5. add `moreMagic` if you need to do anything else to the returned data
@@ -65,4 +67,12 @@ moreMagic:
     property: metadata.caption
 ```
 
+### (ﾉ◕ヮ◕)ﾉ*:・ﾟ✧ "grab the show name and use it to automatically format an image url"
+
+```yaml
+field: showName
+transform: formatUrl
+transformArg: [base image url]/recaps-$DATAFIELD.png ($DATAFIELD is the placeholder in our formatUrl transform)
+```
+
 ☆.。.:*・°☆.。.:*・°☆.。.:*・°☆.。.:*・°☆