Add explicit scope="col" to <th> column headers

site/content/docs/4.3/getting-started/browsers-devices.md

@@ -29,11 +29,11 @@ Generally speaking, Bootstrap supports the latest versions of each major platfor
 <table class="table">
   <thead>
     <tr>
-      <th></th>
-      <th>Chrome</th>
-      <th>Firefox</th>
-      <th>Safari</th>
-      <th>Android Browser &amp; WebView</th>
+      <th scope="col"></th>
+      <th scope="col">Chrome</th>
+      <th scope="col">Firefox</th>
+      <th scope="col">Safari</th>
+      <th scope="col">Android Browser &amp; WebView</th>
     </tr>
   </thead>
   <tbody>
@@ -61,12 +61,12 @@ Similarly, the latest versions of most desktop browsers are supported.
 <table class="table">
   <thead>
     <tr>
-      <th></th>
-      <th>Chrome</th>
-      <th>Firefox</th>
-      <th>Microsoft Edge</th>
-      <th>Opera</th>
-      <th>Safari</th>
+      <th scope="col"></th>
+      <th scope="col">Chrome</th>
+      <th scope="col">Firefox</th>
+      <th scope="col">Microsoft Edge</th>
+      <th scope="col">Opera</th>
+      <th scope="col">Safari</th>
     </tr>
   </thead>
   <tbody>

site/content/docs/4.3/layout/grid.md

@@ -57,24 +57,24 @@ See how aspects of the Bootstrap grid system work across multiple devices with a
 <table class="table">
   <thead>
     <tr>
-      <th></th>
-      <th>
+      <th scope="col"></th>
+      <th scope="col">
         Extra small<br>
         <span class="font-weight-normal">&lt;576px</span>
       </th>
-      <th>
+      <th scope="col">
         Small<br>
         <span class="font-weight-normal">&ge;576px</span>
       </th>
-      <th>
+      <th scope="col">
         Medium<br>
         <span class="font-weight-normal">&ge;768px</span>
       </th>
-      <th>
+      <th scope="col">
         Large<br>
         <span class="font-weight-normal">&ge;992px</span>
       </th>
-      <th>
+      <th scope="col">
         Extra large<br>
         <span class="font-weight-normal">&ge;1200px</span>
       </th>