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

tools/build.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -euo pipefail
+
+MKDOCS_STRICT="${MKDOCS_STRICT:-true}"
+TMPDIR="${RUNNER_TEMP:-$TMPDIR}"
+OUTPUT_DIR="${OUTPUT_DIR:-${TMPDIR}/dist/}"
+# OFFLINE="${OFFLINE:-false}" # This doesn't seem to do anything, set by mkdocs.yml
+MKDOCS_CONFIG="${MKDOCS_CONFIG:-mkdocs/mkdocs.yml}"
+
+STRICT_FLAG=""
+if [ "${MKDOCS_STRICT}" = "true" ]; then
+  STRICT_FLAG="--strict"
+fi
+
+mkdocs build ${STRICT_FLAG} -f $MKDOCS_CONFIG -d $OUTPUT_DIR