add missing errors + remediation

We're working on updating this doc to lower the support cost of managing AADSTS errors. The updates we will be making are centered around errors that we've determined to carry a high support cost (in terms of incidents/cases). As such, this PR addresses two things:
1. This PR adds high support cost errors that are missing from this document, but have remediation present in the ESTS code base. This covers AADSTS errors 500011, 530034, 700011, 700082, 80014, 900561.
2. This PR also addresses high support cost errors that exist in the document but lack remediation information by adding the remediation information from the ESTS code base to this document. This covers AADSTS errors 50020, 50076, 51004, 53003, 50126, 50146, 50013, 50034, 50079, 53000, 650052, 90072, 90002.

This PR does not address:
1. High support cost errors that are missing from this document, but also lack remediation information in the ESTS code base
2. High support cost errors that are present in this document and lack remediation information, but there is no remediation present in the ESTS code base. 
-------
cc: @rwike77

Author: nickludwig