Improve wrapping and hit area of accordion example titles (twbs#29782)

Author: ysds

site/content/docs/4.3/components/collapse.md

@@ -78,7 +78,7 @@ Using the [card]({{< docsref "/components/card" >}}) component, you can extend t
   <div class="card">
     <div class="card-header" id="headingOne">
       <h2 class="mb-0">
-        <button class="btn btn-link" type="button" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
+        <button class="btn btn-link btn-block text-left" type="button" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne">
           Collapsible Group Item #1
         </button>
       </h2>
@@ -93,7 +93,7 @@ Using the [card]({{< docsref "/components/card" >}}) component, you can extend t
   <div class="card">
     <div class="card-header" id="headingTwo">
       <h2 class="mb-0">
-        <button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo">
+        <button class="btn btn-link btn-block text-left collapsed" type="button" data-toggle="collapse" data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo">
           Collapsible Group Item #2
         </button>
       </h2>
@@ -107,7 +107,7 @@ Using the [card]({{< docsref "/components/card" >}}) component, you can extend t
   <div class="card">
     <div class="card-header" id="headingThree">
       <h2 class="mb-0">
-        <button class="btn btn-link collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree">
+        <button class="btn btn-link btn-block text-left collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree">
           Collapsible Group Item #3
         </button>
       </h2>