fpga: make AFU resource name 63 char long
webhook: drop mode from README
webhook: extend mappings description
webhook: tighten CRD definitions
webhook: drop mapping to non-existing afuId
explicitly state mappings names can be in any format
use consistent terminology across fpga webhook and plugin
Currently we have hardcoded mapping from human readable names of
AFs and FPGA regions like arria10-nlb0 to the resource names
produced by the FPGA device plugin. This is not sustainable
long term solution.
Implement CRD based mappings so that a new mapping can be added or
removed dynamically by cluster admins with CRD resources.
