Changing text alignment of <rh-table>'s title

[marionnegp]

We received a question about whether a table's title could be left-aligned by default. This would align with our guidelines about left-aligning text by default and would help if a table scrolls horizontally on a page, like it sometimes does in this docs.redhat.com example.

The issue is that HTML captions align center by default. Instead, @zeroedin suggested adding configurable attributes for alignment:

table {
    & caption {
      caption-side: top | bottom | left | right;
      text-align: left | center | right;
    }
}