Add screenshot to readme (#911)

README.adoc

@@ -14,18 +14,7 @@ image:https://img.shields.io/badge/Say%20Thanks-!-1EAEDB.svg[say thanks,link=mai
 
 Commands, called recipes, are stored in a file called `justfile` with syntax inspired by `make`:
 
-```make
+image:screenshot.png[screenshot]
-build:
-    cc *.c -o main
-
-# test everything
-test-all: build
-    ./test --all
-
-# run a specific test
-test TEST: build
-    ./test --test {{TEST}}
-```
 
 You can then run them with `just RECIPE`:
 

examples/screenshot.just

@@ -0,0 +1,15 @@
+alias b := build
+
+host := `uname -a`
+
+# build main
+build:
+    cc *.c -o main
+
+# test everything
+test-all: build
+    ./test --all
+
+# run a specific test
+test TEST: build
+    ./test --test {{TEST}}