move all other favicon-types into dist/icons folder,

point to icons via link and meta tags,
leave favicon.ico in root old browsers,
added custom jekyll layout file to use the icons
for the project website as well.

https://help.github.com/en/articles/customizing-css-and-html-in-your-jekyll-theme
https://github.com/pages-themes/minimal/blob/master/_layouts/default.html
https://stackoverflow.com/a/48969053

dist/icons/browserconfig.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<browserconfig>
+    <msapplication>
+        <tile>
+            <square150x150logo src="/dist/icons/mstile-150x150.png"/>
+            <TileColor>#b91d47</TileColor>
+        </tile>
+    </msapplication>
+</browserconfig>

dist/icons/site.webmanifest

@@ -3,7 +3,7 @@
     "short_name": "RaspAP",
     "icons": [
         {
-            "src": "/android-chrome-192x192.png",
+            "src": "/dist/icons/android-chrome-192x192.png",
             "sizes": "192x192",
             "type": "image/png"
         }