`Mix.Release` struct documentation incorrect

[LostKobrakai]

Precheck

• For proposing a new feature, please start a discussion on the Elixir Core mailing list: https://groups.google.com/group/elixir-lang-core
• For bugs, do a quick search and make sure the bug has not yet been reported
• Please disclose security vulnerabilities privately at elixir-security@googlegroups.com
• Do not use the issues tracker for guidance, questions or support (try Elixir Forum, Stack Overflow, Slack, etc. instead)
• Finally, be nice and have fun!

Environment

• Elixir & Erlang/OTP versions (elixir --version): master branch
• Operating system:

Current behavior

Mix.Release documentation on :version / :version_path contradicts the code and typespec.

Expected behavior

Documentation matching code and typespec.

[josevalim]

Please do send a PR!