Fixed Broken URL

Fixed issue https://github.com/borgified/test_issue/issues/53

free-programming-books.md

@@ -672,7 +672,7 @@
 
 
 ###COBOL
-* [COBOL Programming Fundamental](http://ibmtc.hust.edu.cn/zos-cobol/cobol/resource/COBOL_Programming_Fundamental.pdf) (PDF)
+* [COBOL Programming Fundamental](http://yusman.staff.gunadarma.ac.id/Downloads/files/33460/COBOL_Programming_Fundamental.pdf) (PDF)
 * [OpenCOBOL 1.1 - Programmer's Guide](http://opencobol.add1tocobol.com/OpenCOBOL%20Programmers%20Guide.pdf) (PDF)