Adding cover page.

manuscript/fundamentals--building-our-own-react.markua

@@ -44,7 +44,6 @@ I see three parts: the name of the tag, the tag's properties, and its children.
 | props    | 'class', 'type', 'disabled' |
 | children | <h1>, <input>, Hello        |
 
-{format: ":number-lines"}
 ```
 tag name: 'div'
 tag prop: 'class'
@@ -312,7 +311,7 @@ function createDOMElement(element) {
 
 To set the props on an element we first clear all the existing props and then loop through the current props, setting them accordingly. Of course we filter out the `children` prop since we use that elsewhere and it isn't intended to be set directly. 
 
-{format: "javascript", caption: "Setting DOM Props"}
+{format: "javascript"}
 ```
 function setDOMProps(element, domElement, prevElement) {
     if (prevElement) {