code: void addTextualCommand(Token token) {
      maybeFinishBasic();
      // appending the empty string violates some invariants about the buffer only ever being extended
      if (token.kind != SoyFileParserConstants.CMD_FULL_NIL) {
        append(token, rawTextCmdToString(token));
      }
      discontinuityReason = Reason.COMMAND;
    }
docs: Add the content for a 'textual' command token, like '{sp}'.