Session modules: header comments point to the docs instead of repeating them

SteamVR debugger and Docker keep only the internals the docs lack; the
screenshots script names package.nix as what prepends its variables.

modules/docker.nix

@@ -1,14 +1,7 @@
-# Rootless Docker as a systemd user service (home-manager can't install a
-# root daemon). SteamOS already provides what it needs: newuidmap/newgidmap
-# with their capabilities in /usr/bin, /etc/subuid and /etc/subgid entries
-# for the user, user namespaces and cgroup v2 delegation.
-# - The socket is in the outer runtime dir (session.runtimeDir): the nested
-#   desktop has its own XDG_RUNTIME_DIR, so the CLI gets DOCKER_HOST as a
-#   default in its wrapper instead of relying on $XDG_RUNTIME_DIR.
-# - Started, never restarted, on switch (session.services.start): a restart
-#   would stop running containers.
-# Nothing is written outside the store by this module; dockerd keeps its data
-# (images, containers, volumes) in ~/.local/share/docker (app data).
+# Rootless Docker as a systemd user service (docs/docker.md). The socket is
+# in the outer runtime dir, so the CLI gets it as a default DOCKER_HOST (the
+# nested desktop has its own XDG_RUNTIME_DIR); the unit is only started on
+# switch, as a restart would stop running containers.
 { config, lib, pkgs, ... }:
 let
   cfg = config.steamFrame.docker;

modules/screenshots/link.sh

@@ -1,4 +1,4 @@
-# steam-frame-nix-screenshots (the module prepends runtime, steam): points
+# steam-frame-nix-screenshots (package.nix prepends runtime, steam): points
 # <runtime>/steam-frame-nix/screenshots (tmpfs), where ~/Pictures/<name>
 # links, to the SteamVR screenshot folder of the Steam account last logged
 # in:

modules/steamvr-debugger.nix

@@ -1,27 +1,10 @@
-# SteamVR web helper debugger: DevTools of the dashboard (vrwebhelper) on
-# 127.0.0.1:8087, for dashboard patches. On automatically (mkDefault) when a
-# patch targets port 8087.
-#
-# The port opens only with VRWebHelper/DebuggerEnabled in
-# ~/.config/openvr/config/steamvr.vrsettings, which SteamVR rewrites from
-# memory, so it can't be a store link or be edited while SteamVR runs. The key
-# is set only while SteamVR runs:
-# - before each start, the steamvr-webhelper-debugger oneshot (drop-in
-#   Wants/After on steamvr.service; ExecStartPre= would be too late, vrserver
-#   starts in the unit's own chain) runs `install.sh steamvr-debugger-arm`:
-#   it keeps the key's value in $XDG_STATE_HOME/steam-frame-nix/
-#   steamvr-debugger.armed (a key already true is the user's own and left
-#   alone), sets the key, and writes a runtime drop-in
-#   ($XDG_RUNTIME_DIR/systemd/user/steamvr.service.d) with a /usr/bin-only
-#   restore script (daemon-reload only when it is new, i.e. once per boot);
-# - when SteamVR stops, that ExecStopPost= puts the value back and removes
-#   .armed. The runtime pieces don't depend on Nix, so this also works after
-#   a rollback or uninstall; they are gone at reboot, and .armed (the only
-#   trace after a power loss) is resolved by the next start or
-#   steam-frame-nix-cleanup.
-# Off: no unit and no drop-in; cleanup restores the key once SteamVR is
-# stopped. Developer Mode forwards the port to 0.0.0.0:8088 (docs/ui-patches.md,
-# "DevTools on the LAN"); our patches use 127.0.0.1 only.
+# SteamVR web helper debugger (docs/steamvr-debugger.md): DevTools of the
+# dashboard on 127.0.0.1:8087, on (mkDefault) when a patch targets port 8087.
+# The steamvr-webhelper-debugger oneshot runs `install.sh steamvr-debugger-arm`
+# before each SteamVR start, through a Wants/After drop-in on steamvr.service
+# (ExecStartPre= would be too late: vrserver starts in the unit's own chain).
+# The arm step reloads systemd only when its runtime drop-in is new (once per
+# boot). Off: no unit and no drop-in; cleanup restores the key.
 { config, lib, pkgs, ... }:
 let
   cfg = config.steamFrame.steamvrDebugger;