Rename chapters into "internals" and "intro"

levels/internals/commit-rhombus/win

@@ -0,0 +1,10 @@
+COMMITS=$(git cat-file --batch-check='%(objectname) %(objecttype)' --batch-all-objects | grep commit | cut -f1 -d" ")
+
+for COMMIT in $COMMITS; do
+    # My first parent's parents has to be the same as my second parent's parent.
+    if [ "$(git rev-parse --verify -q $COMMIT^1^)" = "$(git rev-parse --verify -q $COMMIT^2^)" ]; then
+        return 0
+    fi
+done
+
+return 1