diff --git a/modules/rust.nix b/modules/rust.nix
index 18ba54b..23a6811 100644
--- a/modules/rust.nix
+++ b/modules/rust.nix
@@ -8,6 +8,15 @@
 #   https://rust-analyzer.github.io/
 #   rust-analyzer is an implementation of Language Server Protocol for the Rust programming language. It provides features like completion and goto definition for many code editors, including VS Code, Emacs and Vim.
 
+# pkg-config
+#   Used in these two examples
+#     https://nixos.wiki/wiki/Rust#Custom_Rust_version
+#     https://github.com/oxalica/rust-overlay/blob/master/examples/cross-aarch64/shell.nix
+#   Explanation:
+#     https://nixos.wiki/wiki/Rust#Building_Rust_crates_that_require_external_system_libraries
+#     Rust crates using external system libraries often depend on pkg.config
+#   While we could add it system wide, it is probably best to use a shell.nix file in some code project.
+
 { config, pkgs, ... }:
 let
   #rustVersion = pkgs.rust-bin.stable."1.81.0".default.override {