refresh intro levels 2-4, making them more like a tutorial

levels/chapter_01.json

@@ -22,6 +22,14 @@
 			"id": "digits",
 			"name": "Digits",
 			"description": "place digits and use number keys to assign them values",
+			"init_board": {
+				"grid": "           \n\n\n       o\n     o\n   o\n       1\n   4 8 7\n\n   I I I\n\n\n\n",
+				"comments": [
+					{ "text": "Digit tiles are consumed by marbles that pass over them,\n adding their value to the end of the marble's number", "x": 8, "y": 5 },
+					{ "text": "Try selecting this 7 with the digit tool (#) in your toolbar\n then change it to a 6 using your keyboard number keys", "x": 8, "y": 7 },
+					{ "text": "You can also use the arrow keys to move the selection around,\n if you need to type more numbers", "x": 8, "y": 10 }
+				]
+			},
 			"stages": [{
 				"input": [],
 				"output": [4, 8, 16]
@@ -31,7 +39,14 @@
 			"id": "loop",
 			"name": "Loop",
 			"description": "repeated output",
-			"init_board": "\n   \n o\n\n\n\n ^ \n\n",
+			"init_board": {
+				"grid": "           \n\n\n   v\n   o\n\n   *B  I\n\n\n   ^\n\n\n\n",
+				"comments": [
+					{ "text": "Arrows change the direction of marbles that collide with them", "x": 4, "y": 3 },
+					{ "text": " v Buttons are activated by marbles, and can power other machines", "x": 3, "y": 5 },
+					{ "text": "^ Silos create new marbles when powered", "x": 4, "y": 7 }
+				]
+			},
 			"stages": [{
 				"input": [],
 				"output": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
@@ -41,6 +56,12 @@
 			"id": "copy_input",
 			"name": "Copy Cat",
 			"description": "read input and output the same thing",
+			"init_board": {
+			    "grid": "           \n\n\n   v\n   o\n\n   *I  I\n\n\n   ^\n\n\n\n",
+				"comments": [
+					{ "text": "^ When an input/output silo is powered, it creates a new marble,\n containing the next value from the level input as a number", "x": 4, "y": 7 }
+				]
+			},
 			"stages": [{
 				"input": "Hello, world!",
 				"output": "Hello, world!"