chore(modals): React example cleanup (#4942)

Author: kflournoy-sf

ui/components/docked-composer/__tests__/__snapshots__/index.spec.js.snap

@@ -703,7 +703,6 @@ exports[`renders a docked composer with popout 1`] = `
     aria-labelledby="dialog-heading-id-1"
     aria-modal="true"
     className="slds-modal slds-fade-in-open slds-docked-composer-modal"
-    closeButton="false"
     role="dialog"
     tabIndex="-1"
   >

ui/components/docked-composer/__tests__/index.spec.js

@@ -84,7 +84,7 @@ it('renders a docked composer with popout', () =>
         className="slds-docked-composer-modal"
         aria-labelledby={dialogHeadingId}
         aria-describedby={dialogBodyId}
-        closeButton="false"
+        closeButton={false}
       >
         <ModalContent id="modal-content-id">
           <DockedComposerPanel footer={<Footer />} nestedDialog>

ui/components/docked-composer/base/example.jsx

@@ -333,7 +333,7 @@ export let states = [
           className="slds-docked-composer-modal"
           aria-labelledby={dialogHeadingId}
           aria-describedby={dialogBodyId}
-          closeButton="false"
+          closeButton={false}
         >
           <ModalContent id="modal-content-id">
             <DockedComposerPanel footer={<Footer />} nestedDialog>

ui/components/modals/base/_deprecate.scss

@@ -40,6 +40,7 @@
 }
 
 @include deprecate('4.0.0', 'Please move slds-modal__close outside modal header') {
+
   .slds-modal__header .slds-modal__close {
     position: absolute;
     top: ($square-icon-medium-boundary * -1.25);

ui/components/prompt/__tests__/__snapshots__/index.spec.js.snap

@@ -14,7 +14,6 @@ exports[`Prompt renders a default prompt 1`] = `
     aria-labelledby="prompt-heading-id"
     aria-modal="true"
     className="slds-modal slds-fade-in-open slds-modal_prompt"
-    closeButton="false"
     role="alertdialog"
     tabIndex="0"
   >

ui/components/prompt/base/example.jsx

@@ -19,7 +19,7 @@ export default (
         aria-labelledby="prompt-heading-id"
         aria-describedby="prompt-message-wrapper"
         className="slds-modal_prompt"
-        closeButton="false"
+        closeButton={false}
       >
         <ModalHeader
           className="slds-theme_error slds-theme_alert-texture"

ui/touch/forms/edit-dialog/example.jsx

@@ -24,7 +24,7 @@ const inputId09 = 'input-id-09';
 export default (
   <div className="demo-only" style={{ height: '640px' }}>
     <Modal className="slds-modal_form">
-      <ModalHeader closeButton="false">
+      <ModalHeader closeButton={false}>
         <button className="slds-button slds-button_neutral">Cancel</button>
         <button className="slds-button slds-button_neutral">Save</button>
         <h1

ui/touch/notifications/prompt/example.jsx

@@ -42,7 +42,7 @@ export let states = [
     element: (
       <div className="demo-only" style={{ height: '640px' }}>
         <Backdrop>
-          <Modal closeButton="false">
+          <Modal closeButton={false}>
             <ModalHeader>
               <h1 className="slds-text-heading_medium">
                 Select a New Record Type
@@ -70,7 +70,7 @@ export let states = [
     element: (
       <div className="demo-only" style={{ height: '640px' }}>
         <Backdrop>
-          <Modal closeButton="false">
+          <Modal closeButton={false}>
             <ModalHeader>
               <h1 className="slds-text-heading_medium">Delete Account</h1>
               <p className="slds-m-top_x-small">
@@ -94,7 +94,7 @@ export let states = [
     element: (
       <div className="demo-only" style={{ height: '640px' }}>
         <Backdrop>
-          <Modal closeButton="false">
+          <Modal closeButton={false}>
             <ModalHeader>
               <span className="slds-icon_container slds-icon-action-share-thanks slds-m-bottom_x-small">
                 <SvgIcon