Add line break after the Fibonacci series output

After printing the Fibonacci series, the terminal cursor stays on the same line. Add endl or "\n" after the loop to improve output readability.

Find the file that prints the Fibonacci series, likely main.cpp or a similar source file. Locate the loop that outputs the series and add a newline character (endl or '\n') after it. Compile and run the program to verify the output appears on a new line.

由索引模型根据 Issue 内容生成。