README: Add instructions for building on windows.
Implementation of common traits for MaybeOwnedVector
Little typo fix

- ./hello_world which is not recognized on Windows fixed.
- .exe extension added.
- Little rewriting.
Revert "Update guide.md"

This reverts commit 3f979b05fc7d913af1969b0bf87d7811c318e890.
Revert "Revert "Update guide.md""

This reverts commit bcf04c4a2354de9cfbbedc22cd813b3fa97325ab.