README Updates for Logging Feature

[mliberatore]

What it Does

Marks system log collection iOS 9-only and de-emphasizes it as a feature.

Notes

• The added link won’t work until Hides Default Logging Capabilities on iOS 10+ #206 and Merges develop into master #203 are merged.
• There’s other information about logging in the "Customization" section, but I think the details there can remain. I’d like your opinion, though:

• Supply your own console log collector that aggregates messages from your third-party logging framework of choice by conforming to LogCollector
• Change how logs are viewed by creating your own view controller conforming to LogViewer.

[mbbischoff]

There’s other information about logging in the "Customization" section, but I think the details there can remain. I’d like your opinion, though:

Yeah, those are fine.