CP-23903: Update `vm_set_bios_strings` API
CP-23903: Update `vm_set_bios_strings` API

1) Update doc for the API.
2) Add list of errors that can be raised.

Signed-off-by: Sharad Yadav <0ab5d8dd51ae0f2f9ed283cbbbb7a94d110e3347@citrix.com>

euanh/xen-api,euanh/xen-api,euanh/xen-api,srowe/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,euanh/xen-api,euanh/xen-api,srowe/xen-api,srowe/xen-api