Change name of main branch from master to 'main'

[jonrkarr]

Before changing this a few things need to be changed:

• The .karr_lab_build_utils.yml file in the datanator_rest_api repo and karr_lab_build_utils need to be changed to track the branch to trigger tests for
• docs.karrlab.org should be updated to track the main branch for each repo which won't necessarily be master anymore

In addition to renaming the branch, master would need to be replaced by main in these files and potentially in configuration for Netlify and other configuration

• .circleci/config.yml
• README.md
• scripts/deploy.sh
• src/scenes/About/About.js
• src/scenes/Help/Faq.js

Similar changes should be made to the other datanator repos

• datanator
  • .karr_lab_build_utils.yml
  • docs/conf.py
• datanator_rest_api
  • .karr_lab_build_utils.yml
  • .circleci/config.yml
  • docs/conf.py
  • README.md
• datanator_query_python
  • .karr_lab_build_utils.yml
  • datanator_query_python/util/mongo_util.py
  • docs/conf.py
  • README.md
• datanator_pattern_design
  • this may not require any changes