Add some examples and refer to the issue that led to the RFC

Author: tbu-

text/0000-main-reexport.md

@@ -15,6 +15,23 @@ not for the program entry point `main`. This RFC aims to fix this inconsistency.
 The above mentioned inconsistency means that e.g. you currently cannot use a
 library's exported function as your main function.
 
+Example:
+
+    pub mod foo {
+        pub fn bar() {
+            print("Hello world!");
+        }
+    }
+    pub use foo::bar as main;
+
+Example 2:
+
+    extern crate main_functions;
+    pub use main_functions::rmdir as main;
+
+See also https://github.com/rust-lang/rust/issues/27640 for the corresponding
+issue discussion.
+
 # Detailed design
 
 Use the symbol `main` at the top-level of a crate that is compiled as a program