Update index.md

content/index.md

@@ -16,3 +16,4 @@ Useful links:
 - [Linux System Call Table](https://chromium.googlesource.com/chromiumos/docs/+/master/constants/syscalls.md#arm-32_bit_EABI) - Linux System Call Table (arm & x86)
 - [CPUlator](https://cpulator.01xz.net/) - CPUlator is a Nios II, ARMv7, MIPS, and RISC-V RV32 simulator of a computer system
 - [Active Directory Exploitation Cheat Sheet](https://github.com/S1ckB0y1337/Active-Directory-Exploitation-Cheat-Sheet) -  A cheat sheet that contains common enumeration and attack methods for Windows Active Directory
+- [Nix package versions](https://lazamar.co.uk/nix-versions/) - Find all versions of a package that were available in a channel and the revision you can download it from