diff --git a/.gitignore b/.gitignore
index 89a70f1..cb03c98 100644
--- a/.gitignore
+++ b/.gitignore
@@ -71,3 +71,4 @@ build-iPhoneSimulator/
 # .nfs files are created when an open file is removed but is still being accessed
 .nfs*
 
+input.txt
diff --git a/README.adoc b/README.adoc
new file mode 100644
index 0000000..34dab1c
--- /dev/null
+++ b/README.adoc
@@ -0,0 +1,14 @@
+= Advent of Code - 2021
+
+See https://adventofcode.com/2021.
+
+== Usage
+
+[source,shell]
+----
+./run.rb <puzzle> <part>
+----
+
+where `<puzzle>` is a number from `1` - `25` and part is either `1` or `2`.
+
+Puzzles are implemented as `puzzles/<puzzle>_<part>/{main.rb,input.txt}`.
diff --git a/README.md b/README.md
deleted file mode 100644
index 9134c40..0000000
--- a/README.md
+++ /dev/null
@@ -1,3 +0,0 @@
-# advent-of-code-2021
-
-https://adventofcode.com/2021
\ No newline at end of file