Update README.md

[sidsarasvati]

Updated README.md to list emacs in the list of editors with on the fly linting.

[ghost]

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[ghost]

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[gaearon]

Hi, thanks for PR. Sorry for long reply time. I don’t think we want to get so specific—we’re merely mentioning some of the editors, not providing an exhaustive list. If you feel strongly about this you can contribute a section to Displaying Lint Output in the Editor in template/README.md instead. Thanks!