Rollup merge of rust-lang#27397 - Dangthrimble:master, r=steveklabnik

Clarifications for those new to Rust and Cargo:
* It's a good idea to get rid of the original `main.exe` in project root
* Slight clarification on the use of `main.rs` vs `lib.rs`
* Clarify that the TOML file needs to be in project root

Author: Manishearth

src/doc/trpl/guessing-game.md

@@ -98,8 +98,8 @@ use std::io;
 
 We’ll need to take user input, and then print the result as output. As such, we
 need the `io` library from the standard library. Rust only imports a few things
-into every program, [the ‘prelude’][prelude]. If it’s not in the prelude,
-you’ll have to `use` it directly.
+by default into every program, [the ‘prelude’][prelude]. If it’s not in the
+prelude, you’ll have to `use` it directly.
 
 [prelude]: ../std/prelude/index.html
 

src/doc/trpl/hello-cargo.md

@@ -8,13 +8,13 @@ so it is assumed that Rust projects will use Cargo from the beginning.
 [cratesio]: http://doc.crates.io
 
 Cargo manages three things: building your code, downloading the dependencies
-your code needs, and building those dependencies. At first, your
-program doesn’t have any dependencies, so we’ll only be using the first part of
-its functionality. Eventually, we’ll add more. Since we started off by using
-Cargo, it'll be easy to add later.
+your code needs, and building those dependencies. At first, your program doesn’t
+have any dependencies, so we’ll only be using the first part of its
+functionality. Eventually, we’ll add more. Since we started off by using Cargo,
+it'll be easy to add later.
 
-If you installed Rust via the official installers you will also have Cargo. If
-you installed Rust some other way, you may want to [check the Cargo
+If we installed Rust via the official installers we will also have Cargo. If we
+installed Rust some other way, we may want to [check the Cargo
 README][cargoreadme] for specific instructions about installing it.
 
 [cargoreadme]: https://github.com/rust-lang/cargo#installing-cargo-from-nightlies
@@ -23,20 +23,21 @@ README][cargoreadme] for specific instructions about installing it.
 
 Let’s convert Hello World to Cargo.
 
-To Cargo-ify our project, we need to do two things: Make a `Cargo.toml`
-configuration file, and put our source file in the right place. Let's
-do that part first:
+To Cargo-ify our project, we need to do three things: Make a `Cargo.toml`
+configuration file, put our source file in the right place, and get rid of the
+old executable (`main.exe` on Windows, `main` everywhere else). Let's do that part first:
 
 ```bash
 $ mkdir src
 $ mv main.rs src/main.rs
+$ rm main  # or main.exe on Windows
 ```
 
-Note that since we're creating an executable, we used `main.rs`. If we
-want to make a library instead, we should use `lib.rs`. This convention is required
-for Cargo to successfully compile our projects, but it can be overridden if we wish. 
-Custom file locations for the entry point can be specified
-with a [`[lib]` or `[[bin]]`][crates-custom] key in the TOML file.
+Note that since we're creating an executable, we retain `main.rs` as the source
+filename. If we want to make a library instead, we should use `lib.rs`. This
+convention is used by Cargo to successfully compile our projects, but it can be
+overridden if we wish. Custom file locations for the entry point can be
+specified with a [`[lib]` or `[[bin]]`][crates-custom] key in the TOML file.
 
 [crates-custom]: http://doc.crates.io/manifest.html#configuring-a-target
 
@@ -63,8 +64,8 @@ version = "0.0.1"
 authors = [ "Your name <[email protected]>" ]
 ```
 
-This file is in the [TOML][toml] format. TOML is similar to INI, but has some 
-extra goodies. According to the TOML docs, 
+This file is in the [TOML][toml] format. TOML is similar to INI, but has some
+extra goodies. According to the TOML docs,
 
 > TOML aims to be a minimal configuration file format that's easy to read due
 > to obvious semantics. TOML is designed to map unambiguously to a hash table.
@@ -73,7 +74,8 @@ extra goodies. According to the TOML docs,
 
 [toml]: https://github.com/toml-lang/toml
 
-Once you have this file in place, we should be ready to build! To do so, run:
+Once we have this file in place in our project's root directory, we should be
+ready to build! To do so, run:
 
 ```bash
 $ cargo build