Issues in the Quick Start Guide

I recently started studying Bevy -- notice that I am not a English native speaker, so perhaps I just misunderstand a few points?

For me the most serious issue is at https://bevyengine.org/learn/quick-start/getting-started/apps/

```
What Makes an App? [#](https://bevyengine.org/learn/quick-start/getting-started/apps/#what-makes-an-app)

So, what sort of data does our [App](https://docs.rs/bevy/latest/bevy/app/struct.App.html) really store? Looking at the docs linked, we find three fields: world, schedule, and runner.
```

Even when reading a second time, I have no idea what "docs linked" refers to exactly. Where is the link? What section of the docs? And "we find three fields: world, schedule, and runner." What fields? Fields in a struct? What struct?

A few other, minor issues:

https://bevyengine.org/learn/quick-start/getting-started/setup/

```
Create a new Rust executable project [#](https://bevyengine.org/learn/quick-start/getting-started/setup/#create-a-new-rust-executable-project)

First, navigate to a folder where you want to create your new project. Then, run the following command to create a new folder containing our rust executable project:

cargo new my_bevy_game
cd my_bevy_game

Now run cargo run to build and run your project.
```

For better flow, I would suggest this text:

First, navigate to a folder where you want to create your new project. Then, run the following command to create a new directory containing our rust executable project, and move into it:

cargo new my_bevy_game
cd my_bevy_game

Now type cargo run to build and execute your project.

```
Build Bevy [#](https://bevyengine.org/learn/quick-start/getting-started/setup/#build-bevy)

Now run cargo run again. The Bevy dependencies should start building. This will take some time as you are essentially building an engine from scratch. You will only need to do a full rebuild once. Every build after this one will be fast!
```

The use of run ... run is awkward, and build and rebuild is swapped. Better is

Now type cargo run again. The Bevy dependencies should start building. This will take some time as you are essentially building THE WHOLE engine from scratch. You will only need to do a full build once. Every rebuild after this one will be fast!

The last tiny issue is at https://bevyengine.org/learn/quick-start/getting-started/apps/

```
Nice and simple right? Copy the code above into your main.rs file, then run:

cargo run

in your project folder.
```

For my feeling, the colon after run is wrong, because the sentence continues. And to avoid duplicate "run" terms, we might better use "then execute".

Start with the Quick Start Guide's setup and apps pages at the URLs in the issue, reviewing the quoted passages in context. Improve the wording and clarify what the linked App documentation and its three fields refer to; done means the requested passages read naturally and unambiguously.

Written by the indexing model from the issue text.