(Reuters) – Twitter Inc is gradually making the edit button available for its paid subscribers in the United States, the social media company said on Thursday, days after launching the widely requested feature in Canada, Australia and New Zealand. Twitter users have for years demanded the ability to edit their tweets after publishing them, mostly to fix errors such as typos. However, Twitter and its observers have debated whether allowing tweets to be edited could lead to harmful effects, such as the spread of misinformation. Subscribers who pay $4.99 per month for Twitter Blue will be able to…