README slightly out of date

[alexcfaber]

Just tried to checkout the project to contribute and I ran in to a few issues in building the project locally for iOS and Mac which I would like to address in a PR.

1. The build instructions in ReadMe.md seem out of date and only target Mac building
2. PROVISIONING_PROFILE_SPECIFIER is intentionally left blank. I should have known that; but silly me managed to do this wrong a few times.
3. The XCConfig directory includes multiple xcconfigs which contain the same instructions as in the Readme. But every single one seems to be written against a different state of the process.
   e.g. The Readme is missing iOS development and NetNewsWire_iOSapp_target is referring to BUNDLE_ROOT instead of ORGANIZATION_IDENTIFIER.

Solution would be updating Readme and comments, although I can imagine wanted to centralise this as well.

[vincode-io]

I assume you want this work done on master and not ios-candidate?

[brentsimmons]

Yes. On master.

[brentsimmons]

Removed from the milestone. It is work that needs to be done, but it doesn’t need to be done in order to ship 5.0 for iOS.