Update table-row-context-example.html (#18674)

Fixed comments for each column.

Author: mmalerba

src/components-examples/material/table/table-row-context/table-row-context-example.html

@@ -1,5 +1,5 @@
 <table mat-table [dataSource]="data" class="mat-elevation-z8">
-  <!-- Index Column -->
+  <!-- Implicit Column -->
   <ng-container matColumnDef="$implicit">
     <th mat-header-cell *matHeaderCellDef> $implicit </th>
     <td mat-cell *matCellDef="let data"> {{data}} </td>
@@ -11,31 +11,31 @@
     <td mat-cell *matCellDef="let index = index"> {{index}} </td>
   </ng-container>
 
-  <!-- Index Column -->
+  <!-- Count Column -->
   <ng-container matColumnDef="count">
     <th mat-header-cell *matHeaderCellDef> count </th>
     <td mat-cell *matCellDef="let count = count"> {{count}} </td>
   </ng-container>
 
-  <!-- Index Column -->
+  <!-- First Column -->
   <ng-container matColumnDef="first">
     <th mat-header-cell *matHeaderCellDef> first </th>
     <td mat-cell *matCellDef="let first = first"> {{first}} </td>
   </ng-container>
 
-  <!-- Index Column -->
+  <!-- Last Column -->
   <ng-container matColumnDef="last">
     <th mat-header-cell *matHeaderCellDef> last </th>
     <td mat-cell *matCellDef="let last = last"> {{last}} </td>
   </ng-container>
 
-  <!-- Index Column -->
+  <!-- Even Column -->
   <ng-container matColumnDef="even">
     <th mat-header-cell *matHeaderCellDef> even </th>
     <td mat-cell *matCellDef="let even = even"> {{even}} </td>
   </ng-container>
 
-  <!-- Index Column -->
+  <!-- Odd Column -->
   <ng-container matColumnDef="odd">
     <th mat-header-cell *matHeaderCellDef> odd </th>
     <td mat-cell *matCellDef="let odd = odd"> {{odd}} </td>