Add level template

levels/contrib/template

@@ -0,0 +1,31 @@
+[description]
+
+This text will be shown when the level starts.
+
+It describes the task or puzzle the player can solve.
+
+[congrats]
+
+This text will be shown after the player has solved the level.
+
+Can contain additional information, or bonus exercises.
+
+[setup]
+
+# Bash commands that set up the initial state of the level. An initial
+# `git init` is always done automatically. The default branch is called `main`.
+
+echo You > people_who_are_awesome
+git add .
+git commit -m "Initial commit"
+
+[win]
+
+# Bash commands that check whether the level is solved. Write these as if you're
+# writing the body of a Bash function. Make the function return 0 if it's
+# solved, and a non-zero value otherwise. You can use `return`, and also, Bash
+# functions return the exit code of the last statement, which sometimes allows
+# very succinct checks.
+
+# Check whether the file has at least two lines in the latest commit:
+test "$(git show HEAD:people_who_are_awesome | wc -l)" -ge 2