removing summary attribute content

[fstrr]

Hi

AGWG is planning to remove H73 (Using the summary attribute of the table element to give an overview of data tables) because the summary attribute is obsolete in HTML. H73, and an example of using the summary attribute, are included in the Captions And Summary page, which will need to be updated. See the WCAG old techniques to remove issue.

Thanks

[yatil]

@fstrr I created a pull request for this.

[fstrr]

@yatil Thanks :)