Stix validator update

[delliott90]

Changes to the bundle validator script and documentation to account for stix2-validator using STIX 2.1.

[codecov]

Codecov Report

Merging #838 (b89f99b) into develop (ea4d7e0) will increase coverage by 0.00%.
The diff coverage is 33.33%.

@@           Coverage Diff            @@
##           develop     #838   +/-   ##
========================================
  Coverage    63.79%   63.80%           
========================================
  Files          452      452           
  Lines        39900    39896    -4     
========================================
- Hits         25455    25454    -1     
+ Misses       14445    14442    -3     

Impacted Files	Coverage Δ
...lation/src/json_to_stix/json_to_stix_translator.py	79.15% <33.33%> (+0.64%)	⬆️

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