auto merge of #16235 : cakebaker/rust/rename_modules_rs_to_main_rs, r=steveklabnik

Author: bors

src/doc/guide.md

@@ -2565,9 +2565,9 @@ It gives an error:
 
 ```{notrust,ignore}
    Compiling modules v0.1.0 (file:/home/you/projects/modules)
-src/modules.rs:2:5: 2:23 error: function `print_hello` is private
-src/modules.rs:2     hello::print_hello();
-                     ^~~~~~~~~~~~~~~~~~
+src/main.rs:2:5: 2:23 error: function `print_hello` is private
+src/main.rs:2     hello::print_hello();
+                  ^~~~~~~~~~~~~~~~~~
 ```
 
 To make it public, we use the `pub` keyword: