intro to LinuxBoot implementation

[orangecms]

trafficstars

the current chapter is an example of reworking a given hardware+firmware design by replacing DXEs

move that to its own file, and write an introductory chapter

• elaborate on how LinuxBoot is a concept and many implementations are possible to cover different use cases
• discuss hooking into an existing platform vs design from scratch
• reference the implementation examples

[pamolloy]

Perhaps also worth mentioning https://github.com/BayLibre/k-boot