attributes.asciidoc in j1-template-2023.2.0

- old
+ new
@@ -440,9 +440,33 @@
 
 :url-ruby--​windows-download-v2-7-4:               https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-2.7.4-1/rubyinstaller-devkit-2.7.4-1-x64.exe
 :url-nodejs--​windows-download-remommended:        https://nodejs.org/dist/v12.22.0/node-v12.22.0-x64.msi
 :url-j1--​template-starter:                        https://github.com/jekyll-one/j1-template-starter
 
+:placeholder_image_100x100:                       https://placehold.it/100x100/
+:placeholder_image_200x200:                       https://placehold.it/200x200/
+:placeholder_image_300x300:                       https://placehold.it/300x300/
+:placeholder_image_400x400:                       https://placehold.it/400x400/
+:placeholder_image_500x500:                       https://placehold.it/500x500/
+
+:placeholder_image_100x600:                       https://placehold.it/100x600/
+:placeholder_image_200x600:                       https://placehold.it/200x600/
+:placeholder_image_300x600:                       https://placehold.it/300x600/
+:placeholder_image_400x600:                       https://placehold.it/400x600/
+:placeholder_image_500x600:                       https://placehold.it/500x600/
+
+:placeholder_kitten_100x100:                      https://placekitten.com/100/100/
+:placeholder_kitten_200x200:                      https://placekitten.com/200/200/
+:placeholder_kitten_300x300:                      https://placekitten.com/300/300/
+:placeholder_kitten_400x400:                      https://placekitten.com/400/400/
+:placeholder_kitten_500x500:                      https://placekitten.com/500/500/
+
+:placeholder_kitten_100x600:                      https://placekitten.com/100/600/
+:placeholder_kitten_200x600:                      https://placekitten.com/200/600/
+:placeholder_kitten_300x600:                      https://placekitten.com/300/600/
+:placeholder_kitten_400x600:                      https://placekitten.com/400/600/
+:placeholder_kitten_500x600:                      https://placekitten.com/500/600/
+
 end::urls[]
 
 
 // FOOTNOTES, global asciidoc attributes (variables)
 // -----------------------------------------------------------------------------