Update free-courses-en.md (EbookFoundation#3560)

Author: ninfueng

free-courses-en.md

@@ -447,7 +447,6 @@
 * [SOC Verification Using SystemVerilog](http://verificationexcellence.in/online-courses/soc-verification-using-systemverilog)
 * [SystemVerilog - Learn basics of SystemVerilog for Hardware Verification](https://verificationexcellence.teachable.com/p/learn-systemverilog)
 * [SystemVerilog based UVM Methodology - Learn to build UVM based Testbenches in SystemVerilog](https://verificationexcellence.teachable.com/p/learn-ovm-uvm)
-* [Verilog Hardware Description Language - An Introductory Course](http://vol.verilog.com/VOL/main.htm)
 
 
 ### Web Development