Add space warning: takes +3.75GB

Signed-off-by: axel simon <git@axelsimon.net>

flake.nix

@@ -1,19 +1,21 @@
-# A nix flake that sets up a complete Synapse development environment. Dependencies
+# A Nix flake that sets up a complete Synapse development environment. Dependencies
 # for the SyTest (https://github.com/matrix-org/sytest) and Complement
 # (https://github.com/matrix-org/complement) Matrix homeserver test suites are also
 # installed automatically.
 #
-# You must have already installed nix (https://nixos.org) on your system to use this.
-# nix can be installed on Linux or MacOS; NixOS is not required. Windows is not
-# directly supported, but nix can be installed inside of WSL2 or even Docker
+# You must have already installed Nix (https://nixos.org) on your system to use this.
+# Nix can be installed on Linux or MacOS; NixOS is not required. Windows is not
+# directly supported, but Nix can be installed inside of WSL2 or even Docker
 # containers. Please refer to https://nixos.org/download for details.
 #
 # You must also enable support for flakes in Nix. See the following for how to
 # do so permanently: https://nixos.wiki/wiki/Flakes#Enable_flakes
 #
+# Be warned: you'll need over 3.75 GB of free space to download all the dependencies.
+#
 # Usage:
 #
-# With nix installed, navigate to the directory containing this flake and run
+# With Nix installed, navigate to the directory containing this flake and run
 # `nix develop --impure`. The `--impure` is necessary in order to store state
 # locally from "services", such as PostgreSQL and Redis.
 #
@@ -66,7 +68,7 @@
         let
           pkgs = nixpkgs.legacyPackages.${system};
         in {
-          # Everything is configured via devenv - a nix module for creating declarative
+          # Everything is configured via devenv - a Nix module for creating declarative
           # developer environments. See https://devenv.sh/reference/options/ for a list
           # of all possible options.
           default = devenv.lib.mkShell {
@@ -157,7 +159,7 @@
                 #
                 # This list was compiled by cross-referencing https://metacpan.org/
                 # with the modules defined in './cpanfile' and then finding the
-                # corresponding nix packages on https://search.nixos.org/packages.
+                # corresponding Nix packages on https://search.nixos.org/packages.
                 #
                 # This was done until `./install-deps.pl --dryrun` produced no output.
                 env.PERL5LIB = "${with pkgs.perl536Packages; makePerlPath [