update

Former-commit-id: d8659825a2

docs/scripts/compress_src_png.sh

@@ -1,2 +1,9 @@
-# for file in ./docs/src/*.png
-# optipng $file
+#!/usr/bin/env bash
+
+# Compress png files in ./docs/src
+
+[[ -d "./docs" ]] || (echo "Folder ./docs not found" && exit 1)
+
+for file in ./docs/src/*.png; do
+  optipng "$file"
+done