Update src/items/functions.md

Co-Authored-By: Mazdak Farrokhzad <[email protected]>

Author: gnzlbg

src/items/functions.md

@@ -149,7 +149,7 @@ extern "stdcall" fn new_i32_stdcall() -> i32 { 0 }
 ```
 
 Just as with [external block], when the `extern` keyword is used and the `"ABI` 
-is omitted, the ABI used defaults to `"C"`. That is, this
+is omitted, the ABI used defaults to `"C"`. That is, this:
 
 ```rust
 extern fn new_i32() -> i32 { 0 }