Reorganize resources following Docsy's structure

• Put stylesheets in head and scripts at the end of body;
• Now custom_styles.html and custom_scripts.html are for all pages, head-import and tail-import blocks are for pages of the same layout, and the existing params are for single pages.

Other repos to be updated related to changes here:

• eco-k-o and kate-editor-org: custom-import.html -> custom_styles.html;
• develop-k-o: favicons.html to be removed;
• and apps-k-o which is what led me to doing this: put resources to their places in index.html and applications/single.html.