Add note about Microsoft fork in README

[codecov[bot]]

Codecov Report

Merging #770 (d0b5615) into master (1598eaf) will decrease coverage by 0.22%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #770      +/-   ##
==========================================
- Coverage   71.32%   71.10%   -0.23%     
==========================================
  Files          24       24              
  Lines        5388     5388              
==========================================
- Hits         3843     3831      -12     
- Misses       1301     1309       +8     
- Partials      244      248       +4     

Impacted Files	Coverage Δ
tds.go	64.76% <0.00%> (-1.46%)	:arrow_down:

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