Technical peer review; new intro & appendices

1_checklist_introduction.md

2_readiness_assessment_tool.md

3_directions_and_legend.md

4_device_security_checklist.md

5_authentication_checklist.md

6_wireless_checklist.md

7_email_safety_checklist.md

8_gsuite_security_checklist.md

A_glossary.md

B_threat_model.md

C_FAQ.md

README.md