Clarify rotate_{left,right} docs

I wondered what the `<<!` operator is although the exclamation mark was
only the end of the sentence.

Author: tbu-

src/libcore/num/mod.rs

@@ -346,7 +346,7 @@ $EndFeature, "
             concat!("Shifts the bits to the left by a specified amount, `n`,
 wrapping the truncated bits to the end of the resulting integer.
 
-Please note this isn't the same operation as `<<`!
+Please note this isn't the same operation as the `<<` shifting operator!
 
 # Examples
 
@@ -370,7 +370,7 @@ assert_eq!(n.rotate_left(", $rot, "), m);
 wrapping the truncated bits to the beginning of the resulting
 integer.
 
-Please note this isn't the same operation as `>>`!
+Please note this isn't the same operation as the `>>` shifting operator!
 
 # Examples
 
@@ -2300,7 +2300,7 @@ assert_eq!(n.trailing_zeros(), 3);", $EndFeature, "
             concat!("Shifts the bits to the left by a specified amount, `n`,
 wrapping the truncated bits to the end of the resulting integer.
 
-Please note this isn't the same operation as `<<`!
+Please note this isn't the same operation as the `<<` shifting operator!
 
 # Examples
 
@@ -2324,7 +2324,7 @@ assert_eq!(n.rotate_left(", $rot, "), m);
 wrapping the truncated bits to the beginning of the resulting
 integer.
 
-Please note this isn't the same operation as `>>`!
+Please note this isn't the same operation as the `>>` shifting operator!
 
 # Examples
 

src/libcore/num/wrapping.rs

@@ -429,7 +429,8 @@ assert_eq!(n.trailing_zeros(), 3);
             /// wrapping the truncated bits to the end of the resulting
             /// integer.
             ///
-            /// Please note this isn't the same operation as `>>`!
+            /// Please note this isn't the same operation as the `>>` shifting
+            /// operator!
             ///
             /// # Examples
             ///
@@ -454,7 +455,8 @@ assert_eq!(n.trailing_zeros(), 3);
             /// wrapping the truncated bits to the beginning of the resulting
             /// integer.
             ///
-            /// Please note this isn't the same operation as `<<`!
+            /// Please note this isn't the same operation as the `<<` shifting
+            /// operator!
             ///
             /// # Examples
             ///