Parser library's list of node types: https://github.com/marcandre/parser/blob/master/lib/parser/meta.rb
RuboCop's Creating a New Cop documentation (RuboCop specific, but useful): https://docs.rubocop.org/rubocop/development.html#create-a-new-cop
RuboCop Node Pattern documentation: https://docs.rubocop.org/rubocop-ast/node_pattern.html
RuboCop NodePattern class with query examples: https://github.com/rubocop-hq/rubocop-ast/blob/master/lib/rubocop/ast/node_pattern.rb