[Website] Add ORT at MS page and doc fixes (#12518)
* add ort at microsoft page
* remove openmp references
* update EP table
* update ort-at-microsoft page
* fix link
* Change ORT to ONNX Runtime
Co-authored-by: Nat Kershaw (MSFT) <nakersha@microsoft.com>
Co-authored-by: Nat Kershaw (MSFT) <nakersha@microsoft.com>
