Rollup merge of rust-lang#66619 - guanqun:use-third-person-singular-verb, r=Centril

follow the convention in this file to use third-person singular verbs

Author: Centril

src/libcore/iter/traits/iterator.rs

@@ -1255,7 +1255,7 @@ pub trait Iterator {
         Fuse::new(self)
     }
 
-    /// Do something with each element of an iterator, passing the value on.
+    /// Does something with each element of an iterator, passing the value on.
     ///
     /// When using iterators, you'll often chain several of them together.
     /// While working on such code, you might want to check out what's
@@ -1548,7 +1548,7 @@ pub trait Iterator {
         (left, right)
     }
 
-    /// Reorder the elements of this iterator *in-place* according to the given predicate,
+    /// Reorders the elements of this iterator *in-place* according to the given predicate,
     /// such that all those that return `true` precede all those that return `false`.
     /// Returns the number of `true` elements found.
     ///