Fix .gitignore: stop tracking ignored files

backend/lib/openzeppelin-contracts/scripts/prepare-docs.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+OUTDIR="$(node -p 'require("./docs/config.js").outputDir')"
+
+if [ ! -d node_modules ]; then
+  npm ci
+fi
+
+rm -rf "$OUTDIR"
+
+hardhat docgen
+
+# copy examples and adjust imports
+examples_dir="docs/modules/api/examples"
+mkdir -p "$examples_dir"
+for f in contracts/mocks/docs/*.sol; do
+  name="$(basename "$f")"
+  sed -e '/^import/s|\.\./\.\./|@openzeppelin/contracts/|' "$f" > "docs/modules/api/examples/$name"
+done
+
+node scripts/gen-nav.js "$OUTDIR" > "$OUTDIR/../nav.adoc"