- update links to sources from dotnet/coreclr -> dotnet/runtime/src/coreclr
- fix dead urls (github and non-github) under docs/design/coreclr.
- use https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf as a new home for x64 System V ABI, as http://x86-64.org is now abandoned. Update source files as well.
- normalize “, ” and ’ to ascii " and ' and remove trailing whitespaces in modified files.