Merge amethyst#1879

1879: Small fixes to the pong tutorial r=jojolepro,azriel91 a=Adrijaned

## Description

Fixes amethyst#1873

## Additions

Only doc change

## Removals

Only doc change

## Modifications

Only doc change

## PR Checklist

By placing an x in the boxes I certify that I have:

- [x] Updated the content of the book if this PR would make the book outdated.
- [x] Added a changelog entry if this will impact users, or modified more than 5 lines of Rust that wasn't a doc comment.
- [x] Added unit tests for new code added in this PR.
- [x] Acknowledged that by making this pull request I release this code under an MIT/Apache 2.0 dual licensing scheme.

If this modified or created any rs files:

Not applicable

Co-authored-by: Adrijaned <[email protected]>

Author: bors[bot]

book/src/pong-tutorial/pong-tutorial-01.md

@@ -199,7 +199,13 @@ Then we call `.run()` on `game` which starts the game loop. The game will
 continue to run until our `SimpleState` returns `Trans::Quit`, or when all states
 have been popped off the state machine's stack.
 
-Try compiling the code now. You should be able to see the application start, but nothing
+Now, try compiling the code.
+
+> **Note:** Please note that when compiling the game for the first time, it may
+> take upwards an half an hour. Be assured, though, that subsequent builds of
+> the project will be faster.
+
+You should be able to see the application start, but nothing
 will happen and your terminal will hang until you kill the process. This means that the
 core game loop is running in circles, and is awaiting tasks. Let's give it something
 to do by adding a renderer!
@@ -254,8 +260,8 @@ Those plugins will equip our renderer with the ability to open a window and draw
 
 In this configuration, our window will have a black background.
 If you want to use a different color, you can tweak the RGBA
-values inside `with_clear`. Values range from `0.0` to `1.0`, to get that cool green color
-you can try `[0.00196, 0.23726, 0.21765, 1.0]`.
+values inside `with_clear`. Values range from `0.0` to `1.0`, try using for
+instance `[0.00196, 0.23726, 0.21765, 1.0]` to get a nice cyan-colored window.
 
 > **Note:** This setup code is using Amethyst's `RenderPlugin` trait based system that
 > uses `rendy` crate to define the rendering. If you plan to go beyond the rendering

book/src/pong-tutorial/pong-tutorial-02.md

@@ -48,9 +48,6 @@ initialization code from the Pong code.
     use crate::pong::Pong;
     ```
 
-4. Run `cargo build` to get the Rust compiler to complain about unused
-imports in `main.rs`, and delete these.
-
 ## Get around the World
 
 First, in `pong.rs`, let's add a new method to our `State` implementation: `on_start`.
@@ -159,7 +156,7 @@ Now that our camera is set up, it's time to add the paddles.
 
 ## Our first Component
 
-In this section, you will create the `Paddle` component. The code in this section should go into `pong.rs`.
+Now, we will create the `Paddle` component, all in `pong.rs`.
 
 1. Define constants for the paddle width and height.
 
@@ -518,6 +515,12 @@ are on the sheet. Let's create, right next to it, a file called
 )
 ```
 
+> **Note:** Make sure to pay attention to the kind of parentheses in the ron file.
+> Especially, if you are used to writing JSON or similar format files, you might
+> be tempted to use curly braces there; that will however lead to very 
+> hard-to-debug errors, especially since amethyst will not warn you about that 
+> when compiling.
+
 Finally, we load the file containing the position of each sprite on the sheet.
 
 ```rust,edition2018,no_run,noplaypen