Add option to linkify #channel and @user

[paour]

When the step posts to Slack, #channel and @user aren't autolinked in the text of the message, presumably because the step doesn't instruct Slack to do it.

Could you add an option to enable link_names=1 in the Webhook request?

[viktorbenei]

Great idea @paour !

Feel free to send a PR, or create a feature request at https://discuss.bitrise.io/c/feature-request to bump the priority! (we track issues here too of course, but requests at https://discuss.bitrise.io/c/feature-request with higher votes are prioritized accordingly)

[viktorbenei]

This is now implemented (#22) and the latest version of the step includes this option (turned on by default).

Thanks for the feature request @paour ! :)