auto merge of #15247 : smenardpw/rust/patch-1, r=alexcrichton

./hello_world is not recognized on Windows.
We can type either hello_world or hello_world.exe to run the executable. I chose "hello_world.exe", which seems more conventional on Windows.

diff --combined src/doc/guide.md
index f8af50213b98e9daff56d96426bf1df1d14d09f3,3cbe83718d4aed83c2d1c32b9b967733bb64b8b6..4577c5a86d77582d18c8f9bf19e243d1a6ddb439
--- 1/src/doc/guide.md
--- 2/src/doc/guide.md
+++ b/src/doc/guide.md
@@@ -160,7 -160,7 +160,7 @@@ Save the file, and then type this into 
  
  ```{bash}
  $ rustc hello_world.rs
- $ ./hello_world # just 'hello_world' on Windows
+ $ ./hello_world # or hello_world.exe on Windows
  Hello, world
  ```
  
@@@ -243,7 -243,7 +243,7 @@@ There are now two files: our source cod
  executable (`hello_world.exe` on Windows, `hello_world` everywhere else)
  
  ```{bash}
- $ ./hello_world  # or ./hello_world.exe on Windows
+ $ ./hello_world  # or hello_world.exe on Windows
  ```
  
  This prints out our `Hello, world!` text to our terminal.
@@@ -285,9 -285,8 +285,9 @@@ At first, your program doesn't have an
  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.
  
 -Let's convert Hello World to Cargo. The first thing we need to do is install
 -it. To do this, we need to build it from source. There are no binaries yet.
 +Let's convert Hello World to Cargo. The first thing we need to do to begin using Cargo
 +is to install Cargo. To do this, we need to build it from source. There are no binaries
 +yet.
  
  First, let's go back to our projects directory. We don't want Cargo to
  live in our project!