* Create prereqs.md
Creating an overall .NET Core pre-req native deps file to be able to point people to.
* Update prereqs.md
Responding to PR feedback.
Add guidance for two new issues:
1. WACK failure for apps with native code and "Optimize Code" unchecked
in project properties. Developer experience mode pulls in illegal Store
APIs.
2. Large applications failing compilation in Store. The toolchain
distributed with Windows 10 Tools 1.1 mitigates this.