ReleaseNotes: drop dead sections
ReleaseNotes: drop dead sections

git-svn-id: 42672b9bb47426b7a676b2951937ee8d5bc5f62c@296195 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang