Housekeeping

- Update README
- Run shellcheck on .sh files
- Add helper scripts
- Remove eirene vm variant
- Add post-install checklist

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

scripts/update.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+paths=$(git config --file .gitmodules --name-only --get-regexp path | while read -r line; do
+  path=$(git config --file .gitmodules --get "${line}")
+  url=$(git config --file .gitmodules --get "${line%.*}.url")
+  if [[ ${url} == *"karaolidis"* ]]; then
+    echo "${path}"
+  fi
+done)
+
+for path in ${paths}; do
+  echo "Processing submodule: ${path}"
+
+  cd "${path}" || exit
+  git checkout master
+  git fetch upstream
+  git merge upstream/master
+
+  branches=$(git for-each-ref --format='%(refname:short)' refs/heads/ | grep -v '^master$')
+  for branch in ${branches}; do
+    git checkout "${branch}"
+    git rebase master
+  done
+
+  git checkout integration
+  git push origin --all --force-with-lease
+  git push origin --tags --force-with-lease
+
+  cd - > /dev/null || exit
+done
+
+echo "All submodules updated successfully."
+
+nix flake update