[swift-evolution] [SR-3281] Update swift man page

[Natthan Leong]

Hi everyone,

I have submitted an attempt at updating the swift man(1) page as
Github Pull Request #10241 [1] based on the JIRA ticket SR-3281 [2].

Feedback is welcomed up to the end of Thursday, June 15th, preferably
through discussion in the pull request thread and not through the mailing list.

[1] https://github.com/apple/swift/pull/10241
[2] https://bugs.swift.org/browse/SR-3281

Regards,
Nate @contraultra