Merge in SCDM/sentinel_common_data_model from DEV-24504 to SCDM8.1.0
* commit 'cd518722d85f2248361ebc16ad550eb6899f77e8':
DEV-24504: IIS Guidance-v3, SARS-COV-2-AB Guidance-v1
readme.md edited online with Bitbucket-add 8.1.0 line
readme.md landing page edited online with Bitbucket to include v8.0.0.
delete atoc_scdm810.md
delete 810_overview.md
delete 810_Model Change_Facility_Provider.md
delete 810_history-of-modifications.md
delete 810_Guidance.md
DEV-12995 v8.1.0. front matter pages in markdown
