implement mkdocs, remove pandoc

directory restructuring, remove makefile and build files in repo
moved general play section to new document as playing rules
move assets, styles to docs folder

docs/styles/extra.css

@@ -0,0 +1,10 @@
+@import url('https://fonts.googleapis.com/css2?family=Nunito+Sans:ital,opsz,wght@0,6..12,200..1000;1,6..12,200..1000&display=swap');
+@import url('https://fonts.googleapis.com/css2?family=Merriweather:ital,opsz,wght@0,18..144,300..900;1,18..144,300..900&display=swap');
+
+:root {
+  --md-text-font: "Merriweather"
+}
+
+.md-nav__title {
+  font-family: "Nunito Sans";
+}