Update licensing-service-plan-reference.md

Added SKU details for the following product. 
1. SPE_E5_USGOV_GCCHIGH
2. PROJECTPROFESSIONAL_USGOV_GCCHIGH
3. DESKLESSPACK_USGOV_GCCHIGH
4. EMSPREMIUM_USGOV_GCCHIGH
5. AAD_PREMIUM_USGOV_GCCHIGH
6. ATP_ENTERPRISE_USGOV_GCCHIGH
7. INTUNE_A_VL_USGOV_GCCHIGH
8. MCOACBYOT_AR_GCCHIGH_USGOV_GCCHIGH
9. RIGHTSMANAGEMENT_CE_USGOV_GCCHIGH
10. PHONESYSTEM_VIRTUALUSER_USGOV_GCCHIGH
11. VISIOCLIENT_USGOV_GCCHIGH
12. MCOMEETADV_USGOV_GCCHIGH

Author: Nicholak-MS