Fix article in test

Author: zachs18

tests/ui/lint/for_loop_over_fallibles.rs

@@ -45,7 +45,7 @@ fn _returns_result() -> Result<(), ()> {
 fn _by_ref() {
     // Shared refs
     for _ in &Some(1) {}
-    //~^ WARN for loop over an `&Option`. This is more readably written as an `if let` statement
+    //~^ WARN for loop over a `&Option`. This is more readably written as an `if let` statement
     //~| HELP to check pattern in a loop use `while let`
     //~| HELP consider using `if let` to clear intent
     for _ in &Ok::<_, ()>(1) {}
@@ -55,7 +55,7 @@ fn _by_ref() {
 
     // Mutable refs
     for _ in &mut Some(1) {}
-    //~^ WARN for loop over an `&mut Option`. This is more readably written as an `if let` statement
+    //~^ WARN for loop over a `&mut Option`. This is more readably written as an `if let` statement
     //~| HELP to check pattern in a loop use `while let`
     //~| HELP consider using `if let` to clear intent
     for _ in &mut Ok::<_, ()>(1) {}

tests/ui/lint/for_loop_over_fallibles.stderr

@@ -97,7 +97,7 @@ help: consider using `if let` to clear intent
 LL |     if let Ok(_) = Ok::<_, ()>([0; 0]) {}
    |     ~~~~~~~~~~ ~~~
 
-warning: for loop over an `&Option`. This is more readably written as an `if let` statement
+warning: for loop over a `&Option`. This is more readably written as an `if let` statement
   --> $DIR/for_loop_over_fallibles.rs:47:14
    |
 LL |     for _ in &Some(1) {}
@@ -127,7 +127,7 @@ help: consider using `if let` to clear intent
 LL |     if let Ok(_) = &Ok::<_, ()>(1) {}
    |     ~~~~~~~~~~ ~~~
 
-warning: for loop over an `&mut Option`. This is more readably written as an `if let` statement
+warning: for loop over a `&mut Option`. This is more readably written as an `if let` statement
   --> $DIR/for_loop_over_fallibles.rs:57:14
    |
 LL |     for _ in &mut Some(1) {}