Docs: Fixed info about spanning multiple columns

<img src="{@docRoot}images/ui/gridlayout.png" alt="" />

<p>{@link android.widget.TableLayout} positions its children into rows

    and columns. TableLayout containers do not display border lines for their rows, columns,

    or cells. The table will have as many columns as the row with the most cells. A table can leave

cells empty, but cells cannot span columns, as they can in HTML.</p>

<p>{@link android.widget.TableRow} objects are the child views of a TableLayout

(each TableRow defines a single row in the table).

Each row has zero or more cells, each of which is defined by any kind of other View. So, the cells of a row may be

composed of a variety of View objects, like ImageView or TextView objects.

A cell may also be a ViewGroup object (for example, you can nest another TableLayout as a cell).</p>

<p>The following sample layout has two rows and two cells in each. The accompanying screenshot shows the

result, with cell borders displayed as dotted lines (added for visual effect). </p>

<p>

  {@link android.widget.TableLayout} positions its children into rows and

  columns. TableLayout containers do not display border lines for their rows,

  columns, or cells. The table will have as many columns as the row with the

  most cells. A table can leave cells empty. Cells can span multiple columns,

  as they can in HTML. You can span columns by using the <code>span</code>

  field in the {@link android.widget.TableRow.LayoutParams} class.

</p>

<p class="note">

  <strong>Note:</strong> Cells cannot span multiple rows.

</p>

<p>

  {@link android.widget.TableRow} objects are the child views of a TableLayout

  (each TableRow defines a single row in the table). Each row has zero or more

  cells, each of which is defined by any kind of other View. So, the cells of

  a row may be composed of a variety of View objects, like ImageView or

  TextView objects. A cell may also be a ViewGroup object (for example, you

  can nest another TableLayout as a cell).

</p>

<p>

  The following sample layout has two rows and two cells in each. The

  accompanying screenshot shows the result, with cell borders displayed as

  dotted lines (added for visual effect).

</p>

<table class="columns">

    <tr>