Merge pull request #2046 from ahoppen/ahoppen/optionality-indicators-on-collections

Add a `?` in the `Children` section for optional collections

Author: ahoppen

CodeGeneration/Sources/SyntaxSupport/GrammarGenerator.swift

@@ -37,7 +37,7 @@ struct GrammarGenerator {
       let choicesDescriptions = choices.map { grammar(for: $0) }
       return "(\(choicesDescriptions.joined(separator: " | ")))\(optionality)"
     case .collection(kind: let kind, _, _, _):
-      return "``\(kind.syntaxType)``"
+      return "``\(kind.syntaxType)``\(optionality)"
     case .token(let choices, _, _):
       if choices.count == 1 {
         return "\(grammar(for: choices.first!))\(optionality)"