docs: update nix comment for rust-version in Cargo.toml

Cargo.toml

@@ -9,9 +9,10 @@ readme = "README.md"
 version = "0.6.0-alpha"
 edition = "2021"
 
-# When changing this, change the hash near the text "THE rust-version HASH" in
-# `/flake.nix` too. If you don't have Nix installed or otherwise don't know how
-# to do this, ping `@charles:computer.surgery` in the matrix room.
+# When changing this, make sure to update the `flake.lock` file by running
+# `nix flake update`. If you don't have Nix installed or otherwise don't know
+# how to do this, ping `@charles:computer.surgery` or `@dusk:gaze.systems` in
+# the matrix room.
 rust-version = "1.64.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html